Ran paging and ran area identifier exchange between base stations

ABSTRACT

A first base station receives from a second base station: a cell identifier of a cell of the second base station; and a second radio access network (RAN) area identifier of the cell. A packet for a wireless device in a radio resource control (RRC) inactive state is received. A RAN paging message is sent to the second base station in response to receiving the packet. The RAN paging message is based on a first RAN area identifier of the first base station being identical to the second RAN area identifier.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 16/504,679, filed on Jul. 8, 2019, which will be issued as U.S. Pat.No. 11,064,458 on Jul. 13, 2021, which is a continuation application ofprior Application Ser. No. 15/925,567, filed on Mar. 19, 2018, which hasissued as U.S. Pat. No. 10,349 380 on Jul. 9, 2019; which was based onand claimed the benefit of U.S. Provisional Application No. 62/472,988,filed on Mar. 17, 2017, which is hereby incorporated by reference in itsentirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Examples of several of the various embodiments of the present disclosureare described herein with reference to the drawings.

FIG. 1 is a diagram of an example RAN architecture as per an aspect ofan embodiment of the present disclosure.

FIG. 2A is a diagram of an example user plane protocol stack as per anaspect of an embodiment of the present disclosure.

FIG. 2B is a diagram of an example control plane protocol stack as peran aspect of an embodiment of the present disclosure.

FIG. 3 is a diagram of an example wireless device and two base stationsas per an aspect of an embodiment of the present disclosure.

FIG. 4A, FIG. 4B, FIG. 4C and FIG. 4D are example diagrams for uplinkand downlink signal transmission as per an aspect of an embodiment ofthe present disclosure.

FIG. 5A is a diagram of an example uplink channel mapping and exampleuplink physical signals as per an aspect of an embodiment of the presentdisclosure.

FIG. 5B is a diagram of an example downlink channel mapping and exampledownlink physical signals as per an aspect of an embodiment of thepresent disclosure.

FIG. 6 is a diagram depicting an example frame structure as per anaspect of an embodiment of the present disclosure.

FIG. 7A and FIG. 7B are diagrams depicting example sets of OFDMsubcarriers as per an aspect of an embodiment of the present disclosure.

FIG. 8 is a diagram depicting example OFDM radio resources as per anaspect of an embodiment of the present disclosure.

FIG. 9A, and FIG. 9B are diagrams of an example multi connectivity asper an aspect of an embodiment of the present disclosure.

FIG. 10 is a diagram of an example random access procedure as per anaspect of an embodiment of the present disclosure.

FIG. 11 is a structure of example MAC entities as per an aspect of anembodiment of the present disclosure.

FIG. 12 is a diagram of an example RAN architecture as per an aspect ofan embodiment of the present disclosure.

FIG. 13 is a diagram of example RRC states as per an aspect of anembodiment of the present disclosure.

FIG. 14 is an example diagram as per an aspect of an embodiment of thepresent disclosure.

FIG. 15 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 16 is an example diagram as per an aspect of an embodiment of thepresent disclosure.

FIG. 17 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 18 is an example diagram as per an aspect of an embodiment of thepresent disclosure.

FIG. 19 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 20 is an example diagram as per an aspect of an embodiment of thepresent disclosure.

FIG. 21 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 22 is an example diagram as per an aspect of an embodiment of thepresent disclosure.

FIG. 23 is an example diagram as per an aspect of an embodiment of thepresent disclosure.

FIG. 24 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 25 is an example diagram as per an aspect of an embodiment of thepresent disclosure.

FIG. 26 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 27 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 28 is an example diagram as per an aspect of an embodiment of thepresent disclosure.

FIG. 29 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 30 is an example diagram as per an aspect of an embodiment of thepresent disclosure.

FIG. 31 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 32 is an example diagram as per an aspect of an embodiment of thepresent disclosure.

FIG. 33 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 34 is an example diagram as per an aspect of an embodiment of thepresent disclosure.

FIG. 35 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 36 is an example diagram as per an aspect of an embodiment of thepresent disclosure.

FIG. 37 is an example diagram as per an aspect of an embodiment of thepresent disclosure.

FIG. 38 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 39 is an example diagram as per an aspect of an embodiment of thepresent disclosure.

FIG. 40 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 41 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Example embodiments of the present disclosure enable operation ofcommunication network(s). Embodiments of the technology disclosed hereinmay be employed in the technical field of multicarrier communicationsystems. More particularly, the embodiments of the technology disclosedherein may relate to radio access network(s) in multicarriercommunication systems.

The following Acronyms are used throughout the present disclosure:

3GPP 3rd Generation Partnership Project

5GC 5G Core Network

ACK Acknowledgement

AMF Access and Mobility Management Function

ARQ Automatic Repeat Request

AS Access Stratum

ASIC Application-Specific Integrated Circuit

BA Bandwidth Adaptation

BCCH Broadcast Control Channel

BCH Broadcast Channel

BPSK Binary Phase Shift Keying

BWP Bandwidth Part

CA Carrier Aggregation

CC Component Carrier

CCCH Common Control CHannel

CDMA Code Division Multiple Access

CN Core Network

CP Cyclic Prefix

CP-OFDM Cyclic Prefix-Orthogonal Frequency Division Multiplex

C-RNTI Cell-Radio Network Temporary Identifier

CS Configured Scheduling

CSI Channel State Information

CSI-RS Channel State Information-Reference Signal

CQI Channel Quality Indicator

CSS Common Search Space

CU Central Unit

DC Dual Connectivity

DCCH Dedicated Control CHannel

DCI Downlink Control Information

DL Downlink

DL-SCH Downlink Shared CHannel

DM-RS DeModulation Reference Signal

DRB Data Radio Bearer

DRX Discontinuous Reception

DTCH Dedicated Traffic CHannel

DU Distributed Unit

EPC Evolved Packet Core

E-UTRA Evolved UMTS Terrestrial Radio Access

E-UTRAN Evolved-Universal Terrestrial Radio Access Network

FDD Frequency Division Duplex

FPGA Field Programmable Gate Arrays

F1-C F1-Control plane

F1-U F1-User plane

gNB next generation Node B

HARQ Hybrid Automatic Repeat Request

HDL Hardware Description Languages

IE Information Element

IP Internet Protocol

LCID Logical Channel IDentifier

LTE Long Term Evolution

MAC Media Access Control

MCG Master Cell Group

MCS Modulation and Coding Scheme

MeNB Master evolved Node B

MIB Master Information Block

MME Mobility Management Entity

MN Master Node

NACK Negative Acknowledgement

NAS Non-Access Stratum

NG CP Next Generation Control Plane

NGC Next Generation Core

NG-C NG-Control plane

ng-eNB next generation evolved Node B

NG-U NG-User plane

NR New Radio

NR MAC New Radio MAC

NR PDCP New Radio PDCP

NR PHY New Radio PHYsical

NR RLC New Radio RLC

NR RRC New Radio RRC

NSSAI Network Slice Selection Assistance Information

O&M Operation and Maintenance

OFDM Orthogonal Frequency Division Multiplexing

PBCH Physical Broadcast CHannel

PCC Primary Component Carrier

PCCH Paging Control CHannel

PCell Primary Cell

PCH Paging CHannel

PDCCH Physical Downlink Control CHannel

PDCP Packet Data Convergence Protocol

PDSCH Physical Downlink Shared CHannel

PDU Protocol Data Unit

PHICH Physical HARQ Indicator CHannel

PHY PHYsical

PLMN Public Land Mobile Network

PMI Precoding Matrix Indicator

PRACH Physical Random Access CHannel

PRB Physical Resource Block

PSCell Primary Secondary Cell

PSS Primary Synchronization Signal

pTAG primary Timing Advance Group

PT-RS Phase Tracking Reference Signal

PUCCH Physical Uplink Control CHannel

PUSCH Physical Uplink Shared CHannel

QAM Quadrature Amplitude Modulation

QFI Quality of Service Indicator

QoS Quality of Service

QPSK Quadrature Phase Shift Keying

RA Random Access

RACH Random Access CHannel

RAN Radio Access Network

RAT Radio Access Technology

RA-RNTI Random Access-Radio Network Temporary Identifier

RB Resource Blocks

RBG Resource Block Groups

RI Rank Indicator

RLC Radio Link Control

RRC Radio Resource Control

RS Reference Signal

RSRP Reference Signal Received Power

SCC Secondary Component Carrier

SCell Secondary Cell

SCG Secondary Cell Group

SC-FDMA Single Carrier-Frequency Division Multiple Access

SDAP Service Data Adaptation Protocol

SDU Service Data Unit

SeNB Secondary evolved Node B

SFN System Frame Number

S-GW Serving GateWay

SI System Information

SIB System Information Block

SMF Session Management Function

SN Secondary Node

SpCell Special Cell

SRB Signaling Radio Bearer

SRS Sounding Reference Signal

SS Synchronization Signal

SSS Secondary Synchronization Signal

sTAG secondary Timing Advance Group

TA Timing Advance

TAG Timing Advance Group

TAI Tracking Area Identifier

TAT Time Alignment Timer

TB Transport Block

TC-RNTI Temporary Cell-Radio Network Temporary Identifier

TDD Time Division Duplex

TDMA Time Division Multiple Access

TTI Transmission Time Interval

UCI Uplink Control Information

UE User Equipment

UL Uplink

UL-SCH Uplink Shared CHannel

UPF User Plane Function

UPGW User Plane Gateway

VHDL VHSIC Hardware Description Language

Xn-C Xn-Control plane

Xn-U Xn-User plane

Example embodiments of the disclosure may be implemented using variousphysical layer modulation and transmission mechanisms. Exampletransmission mechanisms may include, but are not limited to: CodeDivision Multiple Access (CDMA), Orthogonal Frequency Division MultipleAccess (OFDMA), Time Division Multiple Access (TDMA), Wavelettechnologies, and/or the like. Hybrid transmission mechanisms such asTDMA/CDMA, and OFDM/CDMA may also be employed. Various modulationschemes may be applied for signal transmission in the physical layer.Examples of modulation schemes include, but are not limited to: phase,amplitude, code, a combination of these, and/or the like. An exampleradio transmission method may implement Quadrature Amplitude Modulation(QAM) using Binary Phase Shift Keying (BPSK), Quadrature Phase ShiftKeying (QPSK), 16-QAM, 64-QAM, 256-QAM, and/or the like. Physical radiotransmission may be enhanced by dynamically or semi-dynamically changingthe modulation and coding scheme depending on transmission requirementsand radio conditions.

FIG. 1 is an example Radio Access Network (RAN) architecture as per anaspect of an embodiment of the present disclosure. As illustrated inthis example, a RAN node may be a next generation Node B (gNB) (e.g.120A, 120B) providing New Radio (NR) user plane and control planeprotocol terminations towards a first wireless device (e.g. 110A). In anexample, a RAN node may be a next generation evolved Node B (ng-eNB)(e.g. 124A, 124B), providing Evolved UMTS Terrestrial Radio Access(E-UTRA) user plane and control plane protocol terminations towards asecond wireless device (e.g. 110B). The first wireless device maycommunicate with a gNB over a Uu interface. The second wireless devicemay communicate with an ng-eNB over a Uu interface. In this disclosure,wireless device 110A and 110B are structurally similar to wirelessdevice 110. Base stations 120A and/or 120B may be structurally similarlyto base station 120. Base station 120 may comprise at least one of a gNB(e.g. 122A and/or 122B), ng-eNB (e.g. 124A and/or 124B), and or thelike.

A gNB or an ng-eNB may host functions such as: radio resource managementand scheduling, IP header compression, encryption and integrityprotection of data, selection of Access and Mobility Management Function(AMF) at User Equipment (UE) attachment, routing of user plane andcontrol plane data, connection setup and release, scheduling andtransmission of paging messages (originated from the AMF), schedulingand transmission of system broadcast information (originated from theAMF or Operation and Maintenance (O&M)), measurement and measurementreporting configuration, transport level packet marking in the uplink,session management, support of network slicing, Quality of Service (QoS)flow management and mapping to data radio bearers, support of UEs inRRC_INACTIVE state, distribution function for Non-Access Stratum (NAS)messages, RAN sharing, and dual connectivity or tight interworkingbetween NR and E-UTRA.

In an example, one or more gNBs and/or one or more ng-eNBs may beinterconnected with each other by means of Xn interface. A gNB or anng-eNB may be connected by means of NG interfaces to 5G Core Network(5GC). In an example, 5GC may comprise one or more AMF/User PlanFunction (UPF) functions (e.g. 130A or 130B). A gNB or an ng-eNB may beconnected to a UPF by means of an NG-User plane (NG-U) interface. TheNG-U interface may provide delivery (e.g. non-guaranteed delivery) ofuser plane Protocol Data Units (PDUs) between a RAN node and the UPF. AgNB or an ng-eNB may be connected to an AMF by means of an NG-Controlplane (NG-C) interface. The NG-C interface may provide, for example, NGinterface management, UE context management, UE mobility management,transport of NAS messages, paging, PDU session management, configurationtransfer and/or warning message transmission, combinations thereof,and/or the like.

In an example, a UPF may host functions such as anchor point forintra-/inter-Radio Access Technology (RAT) mobility (when applicable),external PDU session point of interconnect to data network, packetrouting and forwarding, packet inspection and user plane part of policyrule enforcement, traffic usage reporting, uplink classifier to supportrouting traffic flows to a data network, branching point to supportmulti-homed PDU session, QoS handling for user plane, e.g. packetfiltering, gating, Uplink (UL)/Downlink (DL) rate enforcement, uplinktraffic verification (e.g. Service Data Flow (SDF) to QoS flow mapping),downlink packet buffering and/or downlink data notification triggering.

In an example, an AMF may host functions such as NAS signalingtermination, NAS signaling security, Access Stratum (AS) securitycontrol, inter Core Network (CN) node signaling for mobility between3^(rd) Generation Partnership Project (3GPP) access networks, idle modeUE reachability (e.g., control and execution of paging retransmission),registration area management, support of intra-system and inter-systemmobility, access authentication, access authorization including check ofroaming rights, mobility management control (subscription and policies),support of network slicing and/or Session Management Function (SMF)selection.

FIG. 2A is an example user plane protocol stack, where Service DataAdaptation Protocol (SDAP) (e.g. 211 and 221), Packet Data ConvergenceProtocol (PDCP) (e.g. 212 and 222), Radio Link Control (RLC) (e.g. 213and 223) and Media Access Control (MAC) (e.g. 214 and 224) sublayers andPhysical (PHY) (e.g. 215 and 225) layer may be terminated in wirelessdevice (e.g. 110) and gNB (e.g. 120) on the network side. In an example,a PHY layer provides transport services to higher layers (e.g. MAC, RRC,etc.). In an example, services and functions of a MAC sublayer maycomprise mapping between logical channels and transport channels,multiplexing/demultiplexing of MAC Service Data Units (SDUs) belongingto one or different logical channels into/from Transport Blocks (TBs)delivered to/from the PHY layer, scheduling information reporting, errorcorrection through Hybrid Automatic Repeat request (HARQ) (e.g. one HARQentity per carrier in case of Carrier Aggregation (CA)), priorityhandling between UEs by means of dynamic scheduling, priority handlingbetween logical channels of one UE by means of logical channelprioritization, and/or padding. A MAC entity may support one or multiplenumerologies and/or transmission timings. In an example, mappingrestrictions in a logical channel prioritization may control whichnumerology and/or transmission timing a logical channel may use. In anexample, an RLC sublayer may supports transparent mode (TM),unacknowledged mode (UM) and acknowledged mode (AM) transmission modes.The RLC configuration may be per logical channel with no dependency onnumerologies and/or Transmission Time Interval (TTI) durations. In anexample, Automatic Repeat Request (ARQ) may operate on any of thenumerologies and/or TTI durations the logical channel is configuredwith. In an example, services and functions of the PDCP layer for theuser plane may comprise sequence numbering, header compression anddecompression, transfer of user data, reordering and duplicatedetection, PDCP PDU routing (e.g. in case of split bearers),retransmission of PDCP SDUs, ciphering, deciphering and integrityprotection, PDCP SDU discard, PDCP re-establishment and data recoveryfor RLC AM, and/or duplication of PDCP PDUs. In an example, services andfunctions of SDAP may comprise mapping between a QoS flow and a dataradio bearer. In an example, services and functions of SDAP may comprisemapping Quality of Service Indicator (QFI) in DL and UL packets. In anexample, a protocol entity of SDAP may be configured for an individualPDU session.

FIG. 2B is an example control plane protocol stack where PDCP (e.g. 233and 242), RLC (e.g. 234 and 243) and MAC (e.g. 235 and 244) sublayersand PHY (e.g. 236 and 245) layer may be terminated in wireless device(e.g. 110) and gNB (e.g. 120) on a network side and perform service andfunctions described above. In an example, RRC (e.g. 232 and 241) may beterminated in a wireless device and a gNB on a network side. In anexample, services and functions of RRC may comprise broadcast of systeminformation related to AS and NAS, paging initiated by 5GC or RAN,establishment, maintenance and release of an RRC connection between theUE and RAN, security functions including key management, establishment,configuration, maintenance and release of Signaling Radio Bearers (SRBs)and Data Radio Bearers (DRBs), mobility functions, QoS managementfunctions, UE measurement reporting and control of the reporting,detection of and recovery from radio link failure, and/or NAS messagetransfer to/from NAS from/to a UE. In an example, NAS control protocol(e.g. 231 and 251) may be terminated in the wireless device and AMF(e.g. 130) on a network side and may perform functions such asauthentication, mobility management between a UE and a AMF for 3GPPaccess and non-3GPP access, and session management between a UE and aSMF for 3GPP access and non-3GPP access.

In an example, a base station may configure a plurality of logicalchannels for a wireless device. A logical channel in the plurality oflogical channels may correspond to a radio bearer and the radio bearermay be associated with a QoS requirement. In an example, a base stationmay configure a logical channel to be mapped to one or moreTTIs/numerologies in a plurality of TTIs/numerologies. The wirelessdevice may receive a Downlink Control Information (DCI) via PhysicalDownlink Control CHannel (PDCCH) indicating an uplink grant. In anexample, the uplink grant may be for a first TTI/numerology and mayindicate uplink resources for transmission of a transport block. Thebase station may configure each logical channel in the plurality oflogical channels with one or more parameters to be used by a logicalchannel prioritization procedure at the MAC layer of the wirelessdevice. The one or more parameters may comprise priority, prioritizedbit rate, etc. A logical channel in the plurality of logical channelsmay correspond to one or more buffers comprising data associated withthe logical channel The logical channel prioritization procedure mayallocate the uplink resources to one or more first logical channels inthe plurality of logical channels and/or one or more MAC ControlElements (CEs). The one or more first logical channels may be mapped tothe first TTI/numerology. The MAC layer at the wireless device maymultiplex one or more MAC CEs and/or one or more MAC SDUs (e.g., logicalchannel) in a MAC PDU (e.g., transport block). In an example, the MACPDU may comprise a MAC header comprising a plurality of MAC sub-headers.A MAC sub-header in the plurality of MAC sub-headers may correspond to aMAC CE or a MAC SUD (logical channel) in the one or more MAC CEs and/orone or more MAC SDUs. In an example, a MAC CE or a logical channel maybe configured with a Logical Channel IDentifier (LCID). In an example,LCID for a logical channel or a MAC CE may be fixed/pre-configured. Inan example, LCID for a logical channel or MAC CE may be configured forthe wireless device by the base station. The MAC sub-headercorresponding to a MAC CE or a MAC SDU may comprise LCID associated withthe MAC CE or the MAC SDU.

In an example, a base station may activate and/or deactivate and/orimpact one or more processes (e.g., set values of one or more parametersof the one or more processes or start and/or stop one or more timers ofthe one or more processes) at the wireless device by employing one ormore MAC commands. The one or more MAC commands may comprise one or moreMAC control elements. In an example, the one or more processes maycomprise activation and/or deactivation of PDCP packet duplication forone or more radio bearers. The base station may transmit a MAC CEcomprising one or more fields, the values of the fields indicatingactivation and/or deactivation of PDCP duplication for the one or moreradio bearers. In an example, the one or more processes may compriseChannel State Information (CSI) transmission of on one or more cells.The base station may transmit one or more MAC CEs indicating activationand/or deactivation of the CSI transmission on the one or more cells. Inan example, the one or more processes may comprise activation ordeactivation of one or more secondary cells. In an example, the basestation may transmit a MA CE indicating activation or deactivation ofone or more secondary cells. In an example, the base station maytransmit one or more MAC CEs indicating starting and/or stopping one ormore Discontinuous Reception (DRX) timers at the wireless device. In anexample, the base station may transmit one or more MAC CEs indicatingone or more timing advance values for one or more Timing Advance Groups(TAGs).

FIG. 3 is a block diagram of base stations (base station 1, 120A, andbase station 2, 120B) and a wireless device 110. A wireless device maybe called an UE. A base station may be called a NB, eNB, gNB, and/orng-eNB. In an example, a wireless device and/or a base station may actas a relay node. The base station 1, 120A, may comprise at least onecommunication interface 320A (e.g. a wireless modem, an antenna, a wiredmodem, and/or the like), at least one processor 321A, and at least oneset of program code instructions 323A stored in non-transitory memory322A and executable by the at least one processor 321A. The base station2, 120B, may comprise at least one communication interface 320B, atleast one processor 321B, and at least one set of program codeinstructions 323B stored in non-transitory memory 322B and executable bythe at least one processor 321B.

A base station may comprise many sectors for example: 1, 2, 3, 4, or 6sectors. A base station may comprise many cells, for example, rangingfrom 1 to 50 cells or more. A cell may be categorized, for example, as aprimary cell or secondary cell. At Radio Resource Control (RRC)connection establishment/re-establishment/handover, one serving cell mayprovide the NAS (non-access stratum) mobility information (e.g. TrackingArea Identifier (TAI)). At RRC connection re-establishment/handover, oneserving cell may provide the security input. This cell may be referredto as the Primary Cell (PCell). In the downlink, a carrier correspondingto the PCell may be a DL Primary Component Carrier (PCC), while in theuplink, a carrier may be an UL PCC. Depending on wireless devicecapabilities, Secondary Cells (SCells) may be configured to formtogether with a PCell a set of serving cells. In a downlink, a carriercorresponding to an SCell may be a downlink secondary component carrier(DL SCC), while in an uplink, a carrier may be an uplink secondarycomponent carrier (UL SCC). An S Cell may or may not have an uplinkcarrier.

A cell, comprising a downlink carrier and optionally an uplink carrier,may be assigned a physical cell ID and a cell index. A carrier (downlinkor uplink) may belong to one cell. The cell ID or cell index may alsoidentify the downlink carrier or uplink carrier of the cell (dependingon the context it is used). In the disclosure, a cell ID may be equallyreferred to a carrier ID, and a cell index may be referred to a carrierindex. In an implementation, a physical cell ID or a cell index may beassigned to a cell. A cell ID may be determined using a synchronizationsignal transmitted on a downlink carrier. A cell index may be determinedusing RRC messages. For example, when the disclosure refers to a firstphysical cell ID for a first downlink carrier, the disclosure may meanthe first physical cell ID is for a cell comprising the first downlinkcarrier. The same concept may apply to, for example, carrier activation.When the disclosure indicates that a first carrier is activated, thespecification may equally mean that a cell comprising the first carrieris activated.

A base station may transmit to a wireless device one or more messages(e.g. RRC messages) comprising a plurality of configuration parametersfor one or more cells. One or more cells may comprise at least oneprimary cell and at least one secondary cell. In an example, an RRCmessage may be broadcasted or unicasted to the wireless device. In anexample, configuration parameters may comprise common parameters anddedicated parameters.

Services and/or functions of an RRC sublayer may comprise at least oneof: broadcast of system information related to AS and NAS; paginginitiated by 5GC and/or NG-RAN; establishment, maintenance, and/orrelease of an RRC connection between a wireless device and NG-RAN, whichmay comprise at least one of addition, modification and release ofcarrier aggregation; or addition, modification, and/or release of dualconnectivity in NR or between E-UTRA and NR. Services and/or functionsof an RRC sublayer may further comprise at least one of securityfunctions comprising key management; establishment, configuration,maintenance, and/or release of Signaling Radio Bearers (SRBs) and/orData Radio Bearers (DRBs); mobility functions which may comprise atleast one of a handover (e.g. intra NR mobility or inter-RAT mobility)and a context transfer; or a wireless device cell selection andreselection and control of cell selection and reselection. Servicesand/or functions of an RRC sublayer may further comprise at least one ofQoS management functions; a wireless device measurementconfiguration/reporting; detection of and/or recovery from radio linkfailure; or NAS message transfer to/from a core network entity (e.g.AMF, Mobility Management Entity (MME)) from/to the wireless device.

An RRC sublayer may support an RRC_Idle state, an RRC_Inactive stateand/or an RRC_Connected state for a wireless device. In an RRC_Idlestate, a wireless device may perform at least one of: Public Land MobileNetwork (PLMN) selection; receiving broadcasted system information; cellselection/re-selection; monitoring/receiving a paging for mobileterminated data initiated by 5GC; paging for mobile terminated data areamanaged by 5GC; or DRX for CN paging configured via NAS. In anRRC_Inactive state, a wireless device may perform at least one of:receiving broadcasted system information; cell selection/re-selection;monitoring/receiving a RAN/CN paging initiated by NG-RAN/5GC; RAN-basednotification area (RNA) managed by NG-RAN; or DRX for RAN/CN pagingconfigured by NG-RAN/NAS. In an RRC_Idle state of a wireless device, abase station (e.g. NG-RAN) may keep a 5GC-NG-RAN connection (bothC/U-planes) for the wireless device; and/or store a UE AS context forthe wireless device. In an RRC_Connected state of a wireless device, abase station (e.g. NG-RAN) may perform at least one of: establishment of5GC-NG-RAN connection (both C/U-planes) for the wireless device; storinga UE AS context for the wireless device; transmit/receive of unicastdata to/from the wireless device; or network-controlled mobility basedon measurement results received from the wireless device. In anRRC_Connected state of a wireless device, an NG-RAN may know a cell thatthe wireless device belongs to.

System information (SI) may be divided into minimum SI and other SI. Theminimum SI may be periodically broadcast. The minimum SI may comprisebasic information required for initial access and information foracquiring any other SI broadcast periodically or provisioned on-demand,i.e. scheduling information. The other SI may either be broadcast, or beprovisioned in a dedicated manner, either triggered by a network or uponrequest from a wireless device. A minimum SI may be transmitted via twodifferent downlink channels using different messages (e.g.MasterInformationBlock and SystemInformationBlockType1). Another SI maybe transmitted via SystemInformationBlockType2. For a wireless device inan RRC_Connected state, dedicated RRC signaling may be employed for therequest and delivery of the other SI. For the wireless device in theRRC_Idle state and/or the RRC_Inactive state, the request may trigger arandom-access procedure.

A wireless device may report its radio access capability informationwhich may be static. A base station may request what capabilities for awireless device to report based on band information. When allowed by anetwork, a temporary capability restriction request may be sent by thewireless device to signal the limited availability of some capabilities(e.g. due to hardware sharing, interference or overheating) to the basestation. The base station may confirm or reject the request. Thetemporary capability restriction may be transparent to 5GC (e.g., staticcapabilities may be stored in 5GC).

When CA is configured, a wireless device may have an RRC connection witha network. At RRC connection establishment/re-establishment/handoverprocedure, one serving cell may provide NAS mobility information, and atRRC connection re-establishment/handover, one serving cell may provide asecurity input. This cell may be referred to as the PCell. Depending onthe capabilities of the wireless device, SCells may be configured toform together with the PCell a set of serving cells. The configured setof serving cells for the wireless device may comprise one PCell and oneor more SCells.

The reconfiguration, addition and removal of SCells may be performed byRRC. At intra-NR handover, RRC may also add, remove, or reconfigureSCells for usage with the target PCell. When adding a new SCell,dedicated RRC signaling may be employed to send all required systeminformation of the SCell i.e. while in connected mode, wireless devicesmay not need to acquire broadcasted system information directly from theSCells.

The purpose of an RRC connection reconfiguration procedure may be tomodify an RRC connection, (e.g. to establish, modify and/or release RBs,to perform handover, to setup, modify, and/or release measurements, toadd, modify, and/or release SCells and cell groups). As part of the RRCconnection reconfiguration procedure, NAS dedicated information may betransferred from the network to the wireless device. TheRRCConnectionReconfiguration message may be a command to modify an RRCconnection. It may convey information for measurement configuration,mobility control, radio resource configuration (e.g. RBs, MAC mainconfiguration and physical channel configuration) comprising anyassociated dedicated NAS information and security configuration. If thereceived RRC Connection Reconfiguration message includes thesCellToReleaseList, the wireless device may perform an SCell release. Ifthe received RRC Connection Reconfiguration message includes thesCellToAddModList, the wireless device may perform SCell additions ormodification.

An RRC connection establishment (or reestablishment, resume) proceduremay be to establish (or reestablish, resume) an RRC connection. An RRCconnection establishment procedure may comprise SRB1 establishment. TheRRC connection establishment procedure may be used to transfer theinitial NAS dedicated information/ message from a wireless device toE-UTRAN. The RRCConnectionReestablishment message may be used tore-establish SRB1.

A measurement report procedure may be to transfer measurement resultsfrom a wireless device to NG-RAN. The wireless device may initiate ameasurement report procedure after successful security activation. Ameasurement report message may be employed to transmit measurementresults.

The wireless device 110 may comprise at least one communicationinterface 310 (e.g. a wireless modem, an antenna, and/or the like), atleast one processor 314, and at least one set of program codeinstructions 316 stored in non-transitory memory 315 and executable bythe at least one processor 314. The wireless device 110 may furthercomprise at least one of at least one speaker/microphone 311, at leastone keypad 312, at least one display/touchpad 313, at least one powersource 317, at least one global positioning system (GPS) chipset 318,and other peripherals 319.

The processor 314 of the wireless device 110, the processor 321A of thebase station 1 120A, and/or the processor 321B of the base station 2120B may comprise at least one of a general-purpose processor, a digitalsignal processor (DSP), a controller, a microcontroller, an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA) and/or other programmable logic device, discrete gate and/ortransistor logic, discrete hardware components, and the like. Theprocessor 314 of the wireless device 110, the processor 321A in basestation 1 120A, and/or the processor 321B in base station 2 120B mayperform at least one of signal coding/processing, data processing, powercontrol, input/output processing, and/or any other functionality thatmay enable the wireless device 110, the base station 1 120A and/or thebase station 2 120B to operate in a wireless environment.

The processor 314 of the wireless device 110 may be connected to thespeaker/microphone 311, the keypad 312, and/or the display/touchpad 313.The processor 314 may receive user input data from and/or provide useroutput data to the speaker/microphone 311, the keypad 312, and/or thedisplay/touchpad 313. The processor 314 in the wireless device 110 mayreceive power from the power source 317 and/or may be configured todistribute the power to the other components in the wireless device 110.The power source 317 may comprise at least one of one or more dry cellbatteries, solar cells, fuel cells, and the like. The processor 314 maybe connected to the GPS chipset 318. The GPS chipset 318 may beconfigured to provide geographic location information of the wirelessdevice 110.

The processor 314 of the wireless device 110 may further be connected toother peripherals 319, which may comprise one or more software and/orhardware modules that provide additional features and/orfunctionalities. For example, the peripherals 319 may comprise at leastone of an accelerometer, a satellite transceiver, a digital camera, auniversal serial bus (USB) port, a hands-free headset, a frequencymodulated (FM) radio unit, a media player, an Internet browser, and thelike.

The communication interface 320A of the base station 1, 120A, and/or thecommunication interface 320B of the base station 2, 120B, may beconfigured to communicate with the communication interface 310 of thewireless device 110 via a wireless link 330A and/or a wireless link 330Brespectively. In an example, the communication interface 320A of thebase station 1, 120A, may communicate with the communication interface320B of the base station 2 and other RAN and core network nodes.

The wireless link 330A and/or the wireless link 330B may comprise atleast one of a bi-directional link and/or a directional link. Thecommunication interface 310 of the wireless device 110 may be configuredto communicate with the communication interface 320A of the base station1 120A and/or with the communication interface 320B of the base station2 120B. The base station 1 120A and the wireless device 110 and/or thebase station 2 120B and the wireless device 110 may be configured tosend and receive transport blocks via the wireless link 330A and/or viathe wireless link 330B, respectively. The wireless link 330A and/or thewireless link 330B may employ at least one frequency carrier. Accordingto some of various aspects of embodiments, transceiver(s) may beemployed. A transceiver may be a device that comprises both atransmitter and a receiver. Transceivers may be employed in devices suchas wireless devices, base stations, relay nodes, and/or the like.Example embodiments for radio technology implemented in thecommunication interface 310, 320A, 320B and the wireless link 330A, 330Bare illustrated in FIG. 4A, FIG. 4B, FIG. 4C, FIG. 4D, FIG. 6, FIG. 7A,FIG. 7B, FIG. 8, and associated text.

In an example, other nodes in a wireless network (e.g. AMF, UPF, SMF,etc.) may comprise one or more communication interfaces, one or moreprocessors, and memory storing instructions.

A node (e.g. wireless device, base station, AMF, SMF, UPF, servers,switches, antennas, and/or the like) may comprise one or moreprocessors, and memory storing instructions that when executed by theone or more processors causes the node to perform certain processesand/or functions. Example embodiments may enable operation ofsingle-carrier and/or multi-carrier communications. Other exampleembodiments may comprise a non-transitory tangible computer readablemedia comprising instructions executable by one or more processors tocause operation of single-carrier and/or multi-carrier communications.Yet other example embodiments may comprise an article of manufacturethat comprises a non-transitory tangible computer readablemachine-accessible medium having instructions encoded thereon forenabling programmable hardware to cause a node to enable operation ofsingle-carrier and/or multi-carrier communications. The node may includeprocessors, memory, interfaces, and/or the like.

An interface may comprise at least one of a hardware interface, afirmware interface, a software interface, and/or a combination thereofThe hardware interface may comprise connectors, wires, electronicdevices such as drivers, amplifiers, and/or the like. The softwareinterface may comprise code stored in a memory device to implementprotocol(s), protocol layers, communication drivers, device drivers,combinations thereof, and/or the like. The firmware interface maycomprise a combination of embedded hardware and code stored in and/or incommunication with a memory device to implement connections, electronicdevice operations, protocol(s), protocol layers, communication drivers,device drivers, hardware operations, combinations thereof, and/or thelike.

FIG. 4A, FIG. 4B, FIG. 4C and FIG. 4D are example diagrams for uplinkand downlink signal transmission as per an aspect of an embodiment ofthe present disclosure. FIG. 4A shows an example uplink transmitter forat least one physical channel A baseband signal representing a physicaluplink shared channel may perform one or more functions. The one or morefunctions may comprise at least one of: scrambling; modulation ofscrambled bits to generate complex-valued symbols; mapping of thecomplex-valued modulation symbols onto one or several transmissionlayers; transform precoding to generate complex-valued symbols;precoding of the complex-valued symbols; mapping of precodedcomplex-valued symbols to resource elements; generation ofcomplex-valued time-domain Single Carrier-Frequency Division MultipleAccess (SC-FDMA) or CP-OFDM signal for an antenna port; and/or the like.In an example, when transform precoding is enabled, a SC-FDMA signal foruplink transmission may be generated. In an example, when transformprecoding is not enabled, a CP-OFDM signal for uplink transmission maybe generated by FIG. 4A. These functions are illustrated as examples andit is anticipated that other mechanisms may be implemented in variousembodiments.

An example structure for modulation and up-conversion to the carrierfrequency of the complex-valued SC-FDMA or CP-OFDM baseband signal foran antenna port and/or the complex-valued Physical Random Access CHannel(PRACH) baseband signal is shown in FIG. 4B. Filtering may be employedprior to transmission.

An example structure for downlink transmissions is shown in FIG. 4C. Thebaseband signal representing a downlink physical channel may perform oneor more functions. The one or more functions may comprise: scrambling ofcoded bits in a codeword to be transmitted on a physical channel;modulation of scrambled bits to generate complex-valued modulationsymbols; mapping of the complex-valued modulation symbols onto one orseveral transmission layers; precoding of the complex-valued modulationsymbols on a layer for transmission on the antenna ports; mapping ofcomplex-valued modulation symbols for an antenna port to resourceelements; generation of complex-valued time-domain OFDM signal for anantenna port; and/or the like. These functions are illustrated asexamples and it is anticipated that other mechanisms may be implementedin various embodiments.

In an example, a gNB may transmit a first symbol and a second symbol onan antenna port, to a wireless device. The wireless device may infer thechannel (e.g., fading gain, multipath delay, etc.) for conveying thesecond symbol on the antenna port, from the channel for conveying thefirst symbol on the antenna port. In an example, a first antenna portand a second antenna port may be quasi co-located if one or morelarge-scale properties of the channel over which a first symbol on thefirst antenna port is conveyed may be inferred from the channel overwhich a second symbol on a second antenna port is conveyed. The one ormore large-scale properties may comprise at least one of: delay spread;doppler spread; doppler shift; average gain; average delay; and/orspatial Receiving (Rx) parameters.

An example modulation and up-conversion to the carrier frequency of thecomplex-valued OFDM baseband signal for an antenna port is shown in FIG.4D. Filtering may be employed prior to transmission.

FIG. 5A is a diagram of an example uplink channel mapping and exampleuplink physical signals. FIG. 5B is a diagram of an example downlinkchannel mapping and a downlink physical signals. In an example, aphysical layer may provide one or more information transfer services toa MAC and/or one or more higher layers. For example, the physical layermay provide the one or more information transfer services to the MAC viaone or more transport channels. An information transfer service mayindicate how and with what characteristics data are transferred over theradio interface.

In an example embodiment, a radio network may comprise one or moredownlink and/or uplink transport channels. For example, a diagram inFIG. 5A shows example uplink transport channels comprising Uplink-SharedCHannel (UL-SCH) 501 and Random Access CHannel (RACH) 502. A diagram inFIG. 5B shows example downlink transport channels comprisingDownlink-Shared CHannel (DL-SCH) 511, Paging CHannel (PCH) 512, andBroadcast CHannel (BCH) 513. A transport channel may be mapped to one ormore corresponding physical channels. For example, UL-SCH 501 may bemapped to Physical Uplink Shared CHannel (PUSCH) 503. RACH 502 may bemapped to PRACH 505. DL-SCH 511 and PCH 512 may be mapped to PhysicalDownlink Shared CHannel (PDSCH) 514. BCH 513 may be mapped to PhysicalBroadcast CHannel (PBCH) 516.

There may be one or more physical channels without a correspondingtransport channel The one or more physical channels may be employed forUplink Control Information (UCI) 509 and/or Downlink Control Information(DCI) 517. For example, Physical Uplink Control CHannel (PUCCH) 504 maycarry UCI 509 from a UE to a base station. For example, PhysicalDownlink Control CHannel (PDCCH) 515 may carry DCI 517 from a basestation to a UE. NR may support UCI 509 multiplexing in PUSCH 503 whenUCI 509 and PUSCH 503 transmissions may coincide in a slot at least inpart. The UCI 509 may comprise at least one of CSI, Acknowledgement(ACK)/Negative Acknowledgement (NACK), and/or scheduling request. TheDCI 517 on PDCCH 515 may indicate at least one of following: one or moredownlink assignments and/or one or more uplink scheduling grants

In uplink, a UE may transmit one or more Reference Signals (RSs) to abase station. For example, the one or more RSs may be at least one ofDemodulation-RS (DM-RS) 506, Phase Tracking-RS (PT-RS) 507, and/orSounding RS (SRS) 508. In downlink, a base station may transmit (e.g.,unicast, multicast, and/or broadcast) one or more RSs to a UE. Forexample, the one or more RSs may be at least one of PrimarySynchronization Signal (PSS)/Secondary Synchronization Signal (SSS) 521,CSI-RS 522, DM-RS 523, and/or PT-RS 524.

In an example, a UE may transmit one or more uplink DM-RSs 506 to a basestation for channel estimation, for example, for coherent demodulationof one or more uplink physical channels (e.g., PUSCH 503 and/or PUCCH504). For example, a UE may transmit a base station at least one uplinkDM-RS 506 with PUSCH 503 and/or PUCCH 504, wherein the at least oneuplink DM-RS 506 may be spanning a same frequency range as acorresponding physical channel In an example, a base station mayconfigure a UE with one or more uplink DM-RS configurations. At leastone DM-RS configuration may support a front-loaded DM-RS pattern. Afront-loaded DM-RS may be mapped over one or more OFDM symbols (e.g., 1or 2 adjacent OFDM symbols). One or more additional uplink DM-RS may beconfigured to transmit at one or more symbols of a PUSCH and/or PUCCH. Abase station may semi-statistically configure a UE with a maximum numberof front-loaded DM-RS symbols for PUSCH and/or PUCCH. For example, a UEmay schedule a single-symbol DM-RS and/or double symbol DM-RS based on amaximum number of front-loaded DM-RS symbols, wherein a base station mayconfigure the UE with one or more additional uplink DM-RS for PUSCHand/or PUCCH. A new radio network may support, e.g., at least forCP-OFDM, a common DM-RS structure for DL and UL, wherein a DM-RSlocation, DM-RS pattern, and/or scrambling sequence may be same ordifferent.

In an example, whether uplink PT-RS 507 is present or not may depend ona RRC configuration. For example, a presence of uplink PT-RS may beUE-specifically configured. For example, a presence and/or a pattern ofuplink PT-RS 507 in a scheduled resource may be UE-specificallyconfigured by a combination of RRC signaling and/or association with oneor more parameters employed for other purposes (e.g., Modulation andCoding Scheme (MCS)) which may be indicated by DCI. When configured, adynamic presence of uplink PT-RS 507 may be associated with one or moreDCI parameters comprising at least MCS. A radio network may supportplurality of uplink PT-RS densities defined in time/frequency domain.When present, a frequency domain density may be associated with at leastone configuration of a scheduled bandwidth. A UE may assume a sameprecoding for a DMRS port and a PT-RS port. A number of PT-RS ports maybe less than a number of DM-RS ports in a scheduled resource. Forexample, uplink PT-RS 507 may be confined in the scheduledtime/frequency duration for a UE.

In an example, a UE may transmit SRS 508 to a base station for channelstate estimation to support uplink channel dependent scheduling and/orlink adaptation. For example, SRS 508 transmitted by a UE may allow fora base station to estimate an uplink channel state at one or moredifferent frequencies. A base station scheduler may employ an uplinkchannel state to assign one or more resource blocks of good quality foran uplink PUSCH transmission from a UE. A base station maysemi-statistically configure a UE with one or more SRS resource sets.For an SRS resource set, a base station may configure a UE with one ormore SRS resources. An SRS resource set applicability may be configuredby a higher layer (e.g., RRC) parameter. For example, when a higherlayer parameter indicates beam management, a SRS resource in each of oneor more SRS resource sets may be transmitted at a time instant. A UE maytransmit one or more SRS resources in different SRS resource setssimultaneously. A new radio network may support aperiodic, periodicand/or semi-persistent SRS transmissions. A UE may transmit SRSresources based on one or more trigger types, wherein the one or moretrigger types may comprise higher layer signaling (e.g., RRC) and/or oneor more DCI formats (e.g., at least one DCI format may be employed for aUE to select at least one of one or more configured SRS resource sets.An SRS trigger type 0 may refer to an SRS triggered based on a higherlayer signaling. An SRS trigger type 1 may refer to an SRS triggeredbased on one or more DCI formats. In an example, when PUSCH 503 and SRS508 are transmitted in a same slot, a UE may be configured to transmitSRS 508 after a transmission of PUSCH 503 and corresponding uplink DM-RS506.

In an example, a base station may semi-statistically configure a UE withone or more SRS configuration parameters indicating at least one offollowing: a SRS resource configuration identifier, a number of SRSports, time domain behavior of SRS resource configuration (e.g., anindication of periodic, semi-persistent, or aperiodic SRS), slot(mini-slot, and/or subframe) level periodicity and/or offset for aperiodic and/or aperiodic SRS resource, a number of OFDM symbols in aSRS resource, starting OFDM symbol of a SRS resource, a SRS bandwidth, afrequency hopping bandwidth, a cyclic shift, and/or a SRS sequence ID.

In an example, in a time domain, an SS/PBCH block may comprise one ormore OFDM symbols (e.g., 4 OFDM symbols numbered in increasing orderfrom 0 to 3) within the SS/PBCH block. An SS/PBCH block may comprisePSS/SSS 521 and PBCH 516. In an example, in the frequency domain, anSS/PBCH block may comprise one or more contiguous subcarriers (e.g., 240contiguous subcarriers with the subcarriers numbered in increasing orderfrom 0 to 239) within the SS/PBCH block. For example, a PSS/SSS 521 mayoccupy 1 OFDM symbol and 127 subcarriers. For example, PBCH 516 may spanacross 3 OFDM symbols and 240 subcarriers. A UE may assume that one ormore SS/PBCH blocks transmitted with a same block index may be quasico-located, e.g., with respect to Doppler spread, Doppler shift, averagegain, average delay, and spatial Rx parameters. A UE may not assumequasi co-location for other SS/PBCH block transmissions. A periodicityof an SS/PBCH block may be configured by a radio network (e.g., by anRRC signaling) and one or more time locations where the SS/PBCH blockmay be sent may be determined by sub-carrier spacing. In an example, aUE may assume a band-specific sub-carrier spacing for an SS/PBCH blockunless a radio network has configured a UE to assume a differentsub-carrier spacing.

In an example, downlink CSI-RS 522 may be employed for a UE to acquirechannel state information. A radio network may support periodic,aperiodic, and/or semi-persistent transmission of downlink CSI-RS 522.For example, a base station may semi-statistically configure and/orreconfigure a UE with periodic transmission of downlink CSI-RS 522. Aconfigured CSI-RS resources may be activated ad/or deactivated. Forsemi-persistent transmission, an activation and/or deactivation ofCSI-RS resource may be triggered dynamically. In an example, CSI-RSconfiguration may comprise one or more parameters indicating at least anumber of antenna ports. For example, a base station may configure a UEwith 32 ports. A base station may semi-statistically configure a UE withone or more CSI-RS resource sets. One or more CSI-RS resources may beallocated from one or more CSI-RS resource sets to one or more UEs. Forexample, a base station may semi-statistically configure one or moreparameters indicating CSI RS resource mapping, for example, time-domainlocation of one or more CSI-RS resources, a bandwidth of a CSI-RSresource, and/or a periodicity. In an example, a UE may be configured toemploy a same OFDM symbols for downlink CSI-RS 522 and control resourceset (coreset) when the downlink CSI-RS 522 and coreset are spatiallyquasi co-located and resource elements associated with the downlinkCSI-RS 522 are the outside of PRBs configured for coreset. In anexample, a UE may be configured to employ a same OFDM symbols fordownlink CSI-RS 522 and SSB/PBCH when the downlink CSI-RS 522 andSSB/PBCH are spatially quasi co-located and resource elements associatedwith the downlink CSI-RS 522 are the outside of PRBs configured forSSB/PBCH.

In an example, a UE may transmit one or more downlink DM-RSs 523 to abase station for channel estimation, for example, for coherentdemodulation of one or more downlink physical channels (e.g., PDSCH514). For example, a radio network may support one or more variableand/or configurable DM-RS patterns for data demodulation. At least onedownlink DM-RS configuration may support a front-loaded DM-RS pattern. Afront-loaded DM-RS may be mapped over one or more OFDM symbols (e.g., 1or 2 adjacent OFDM symbols). A base station may semi-statisticallyconfigure a UE with a maximum number of front-loaded DM-RS symbols forPDSCH 514. For example, a DM-RS configuration may support one or moreDM-RS ports. For example, for single user-MIMO, a DM-RS configurationmay support at least 8 orthogonal downlink DM-RS ports. For example, formultiuser-MIMO, a DM-RS configuration may support 12 orthogonal downlinkDM-RS ports. A radio network may support, e.g., at least for CP-OFDM, acommon DM-RS structure for DL and UL, wherein a DM-RS location, DM-RSpattern, and/or scrambling sequence may be same or different.

In an example, whether downlink PT-RS 524 is present or not may dependon a RRC configuration. For example, a presence of downlink PT-RS 524may be UE-specifically configured. For example, a presence and/or apattern of downlink PT-RS 524 in a scheduled resource may beUE-specifically configured by a combination of RRC signaling and/orassociation with one or more parameters employed for other purposes(e.g., MCS) which may be indicated by DCI. When configured, a dynamicpresence of downlink PT-RS 524 may be associated with one or more DCIparameters comprising at least MCS. A radio network may supportplurality of PT-RS densities defined in time/frequency domain. Whenpresent, a frequency domain density may be associated with at least oneconfiguration of a scheduled bandwidth. A UE may assume a same precodingfor a DMRS port and a PT-RS port. A number of PT-RS ports may be lessthan a number of DM-RS ports in a scheduled resource. For example,downlink PT-RS 524 may be confined in the scheduled time/frequencyduration for a UE.

FIG. 6 is a diagram depicting an example frame structure for a carrieras per an aspect of an embodiment of the present disclosure. Amulticarrier OFDM communication system may include one or more carriers,for example, ranging from 1 to 32 carriers, in case of carrieraggregation, or ranging from 1 to 64 carriers, in case of dualconnectivity. Different radio frame structures may be supported (e.g.,for FDD and for TDD duplex mechanisms). FIG. 6 shows an example framestructure. Downlink and uplink transmissions may be organized into radioframes 601. In this example, radio frame duration is 10 ms. In thisexample, a 10 ms radio frame 601 may be divided into ten equally sizedsubframes 602 with 1 ms duration. Subframe(s) may comprise one or moreslots (e.g. slots 603 and 605) depending on subcarrier spacing and/or CPlength. For example, a subframe with 15 kHz, 30 kHz, 60 kHz, 120 kHz,240 kHz and 480 kHz subcarrier spacing may comprise one, two, four,eight, sixteen and thirty-two slots, respectively. In FIG. 6, a subframemay be divided into two equally sized slots 603 with 0.5 ms duration.For example, 10 subframes may be available for downlink transmission and10 subframes may be available for uplink transmissions in a 10 msinterval. Uplink and downlink transmissions may be separated in thefrequency domain. Slot(s) may include a plurality of OFDM symbols 604.The number of OFDM symbols 604 in a slot 605 may depend on the cyclicprefix length. For example, a slot may be 14 OFDM symbols for the samesubcarrier spacing of up to 480 kHz with normal CP. A slot may be 12OFDM symbols for the same subcarrier spacing of 60 kHz with extended CP.A slot may contain downlink, uplink, or a downlink part and an uplinkpart and/or alike.

FIG. 7A is a diagram depicting example sets of OFDM subcarriers as peran aspect of an embodiment of the present disclosure. In the example, agNB may communicate with a wireless device with a carrier with anexample channel bandwidth 700. Arrow(s) in the diagram may depict asubcarrier in a multicarrier OFDM system. The OFDM system may usetechnology such as OFDM technology, SC-FDMA technology, and/or the like.In an example, an arrow 701 shows a subcarrier transmitting informationsymbols. In an example, a subcarrier spacing 702, between two contiguoussubcarriers in a carrier, may be any one of 15 KHz, 30 KHz, 60 KHz, 120KHz, 240 KHz, etc. In an example, different subcarrier spacing maycorrespond to different transmission numerologies. In an example, atransmission numerology may comprise at least: a numerology index; avalue of subcarrier spacing; a type of cyclic prefix (CP). In anexample, a gNB may transmit to/receive from a UE on a number ofsubcarriers 703 in a carrier. In an example, a bandwidth occupied by anumber of subcarriers 703 (transmission bandwidth) may be smaller thanthe channel bandwidth 700 of a carrier, due to guard band 704 and 705.In an example, a guard band 704 and 705 may be used to reduceinterference to and from one or more neighbor carriers. A number ofsubcarriers (transmission bandwidth) in a carrier may depend on thechannel bandwidth of the carrier and the subcarrier spacing. Forexample, a transmission bandwidth, for a carrier with 20 MHz channelbandwidth and 15 KHz subcarrier spacing, may be in number of 1024subcarriers.

In an example, a gNB and a wireless device may communicate with multipleCCs when configured with CA. In an example, different component carriersmay have different bandwidth and/or subcarrier spacing, if CA issupported. In an example, a gNB may transmit a first type of service toa UE on a first component carrier. The gNB may transmit a second type ofservice to the UE on a second component carrier. Different type ofservices may have different service requirement (e.g., data rate,latency, reliability), which may be suitable for transmission viadifferent component carrier having different subcarrier spacing and/orbandwidth. FIG. 7B shows an example embodiment. A first componentcarrier may comprise a first number of subcarriers 706 with a firstsubcarrier spacing 709. A second component carrier may comprise a secondnumber of subcarriers 707 with a second subcarrier spacing 710. A thirdcomponent carrier may comprise a third number of subcarriers 708 with athird subcarrier spacing 711. Carriers in a multicarrier OFDMcommunication system may be contiguous carriers, non-contiguouscarriers, or a combination of both contiguous and non-contiguouscarriers.

FIG. 8 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present disclosure. In an example, a carrier mayhave a transmission bandwidth 801. In an example, a resource grid may bein a structure of frequency domain 802 and time domain 803. In anexample, a resource grid may comprise a first number of OFDM symbols ina subframe and a second number of resource blocks, starting from acommon resource block indicated by higher-layer signaling (e.g. RRCsignaling), for a transmission numerology and a carrier. In an example,in a resource grid, a resource unit identified by a subcarrier index anda symbol index may be a resource element 805. In an example, a subframemay comprise a first number of OFDM symbols 807 depending on anumerology associated with a carrier. For example, when a subcarrierspacing of a numerology of a carrier is 15 KHz, a subframe may have 14OFDM symbols for a carrier. When a subcarrier spacing of a numerology is30 KHz, a subframe may have 28 OFDM symbols. When a subcarrier spacingof a numerology is 60 Khz, a subframe may have 56 OFDM symbols, etc. Inan example, a second number of resource blocks comprised in a resourcegrid of a carrier may depend on a bandwidth and a numerology of thecarrier.

As shown in FIG. 8, a resource block 806 may comprise 12 subcarriers. Inan example, multiple resource blocks may be grouped into a ResourceBlock Group (RBG) 804. In an example, a size of a RBG may depend on atleast one of: a RRC message indicating a RBG size configuration; a sizeof a carrier bandwidth; or a size of a bandwidth part of a carrier. Inan example, a carrier may comprise multiple bandwidth parts. A firstbandwidth part of a carrier may have different frequency location and/orbandwidth from a second bandwidth part of the carrier.

In an example, a gNB may transmit a downlink control informationcomprising a downlink or uplink resource block assignment to a wirelessdevice. A base station may transmit to or receive from, a wirelessdevice, data packets (e.g. transport blocks) scheduled and transmittedvia one or more resource blocks and one or more slots according toparameters in a downlink control information and/or RRC message(s). Inan example, a starting symbol relative to a first slot of the one ormore slots may be indicated to the wireless device. In an example, a gNBmay transmit to or receive from, a wireless device, data packetsscheduled on one or more RBGs and one or more slots.

In an example, a gNB may transmit a downlink control informationcomprising a downlink assignment to a wireless device via one or morePDCCHs. The downlink assignment may comprise parameters indicating atleast modulation and coding format; resource allocation; and/or HARQinformation related to DL-SCH. In an example, a resource allocation maycomprise parameters of resource block allocation; and/or slotallocation. In an example, a gNB may dynamically allocate resources to awireless device via a Cell-Radio Network Temporary Identifier (C-RNTI)on one or more PDCCHs. The wireless device may monitor the one or morePDCCHs in order to find possible allocation when its downlink receptionis enabled. The wireless device may receive one or more downlink datapackage on one or more PDSCH scheduled by the one or more PDCCHs, whensuccessfully detecting the one or more PDCCHs.

In an example, a gNB may allocate Configured Scheduling (CS) resourcesfor down link transmission to a wireless device. The gNB may transmitone or more RRC messages indicating a periodicity of the CS grant. ThegNB may transmit a DCI via a PDCCH addressed to a ConfiguredScheduling-RNTI (CS-RNTI) activating the CS resources. The DCI maycomprise parameters indicating that the downlink grant is a CS grant.The CS grant may be implicitly reused according to the periodicitydefined by the one or more RRC messages, until deactivated.

In an example, a gNB may transmit a downlink control informationcomprising an uplink grant to a wireless device via one or more PDCCHs.The uplink grant may comprise parameters indicating at least modulationand coding format; resource allocation; and/or HARQ information relatedto UL-SCH. In an example, a resource allocation may comprise parametersof resource block allocation; and/or slot allocation. In an example, agNB may dynamically allocate resources to a wireless device via a C-RNTIon one or more PDCCHs. The wireless device may monitor the one or morePDCCHs in order to find possible resource allocation. The wirelessdevice may transmit one or more uplink data package via one or morePUSCH scheduled by the one or more PDCCHs, when successfully detectingthe one or more PDCCHs.

In an example, a gNB may allocate CS resources for uplink datatransmission to a wireless device. The gNB may transmit one or more RRCmessages indicating a periodicity of the CS grant. The gNB may transmita DCI via a PDCCH addressed to a CS-RNTI activating the CS resources.The DCI may comprise parameters indicating that the uplink grant is a CSgrant. The CS grant may be implicitly reused according to theperiodicity defined by the one or more RRC message, until deactivated.

In an example, a base station may transmit DCI/control signaling viaPDCCH. The DCI may take a format in a plurality of formats. A DCI maycomprise downlink and/or uplink scheduling information (e.g., resourceallocation information, HARQ related parameters, MCS), request for CSI(e.g., aperiodic CQI reports), request for SRS, uplink power controlcommands for one or more cells, one or more timing information (e.g., TBtransmission/reception timing, HARQ feedback timing, etc.), etc. In anexample, a DCI may indicate an uplink grant comprising transmissionparameters for one or more transport blocks. In an example, a DCI mayindicate downlink assignment indicating parameters for receiving one ormore transport blocks. In an example, a DCI may be used by base stationto initiate a contention-free random access at the wireless device. Inan example, the base station may transmit a DCI comprising slot formatindicator (SFI) notifying a slot format. In an example, the base stationmay transmit a DCI comprising pre-emption indication notifying thePRB(s) and/or OFDM symbol(s) where a UE may assume no transmission isintended for the UE. In an example, the base station may transmit a DCIfor group power control of PUCCH or PUSCH or SRS. In an example, a DCImay correspond to an RNTI. In an example, the wireless device may obtainan RNTI in response to completing the initial access (e.g., C-RNTI). Inan example, the base station may configure an RNTI for the wireless(e.g., CS-RNTI, TPC-CS-RNTI, TPC-PUCCH-RNTI, TPC-PUSCH-RNTI, andTPC-SRS-RNTI). In an example, the wireless device may compute an RNTI(e.g., the wireless device may compute RA-RNTI based on resources usedfor transmission of a preamble). In an example, an RNTI may have apre-configured value (e.g., P-RNTI or SI-RNTI). In an example, awireless device may monitor a group common search space which may beused by base station for transmitting DCIs that are intended for a groupof UEs. In an example, a group common DCI may correspond to an RNTIwhich is commonly configured for a group of UEs. In an example, awireless device may monitor a UE-specific search space. In an example, aUE specific DCI may correspond to an RNTI configured for the wirelessdevice.

A NR system may support a single beam operation and/or a multi-beamoperation. In a multi-beam operation, a base station may perform adownlink beam sweeping to provide coverage for common control channelsand/or downlink SS blocks, which may comprise at least a PSS, a SSS,and/or PBCH. A wireless device may measure quality of a beam pair linkusing one or more RSs. One or more SS blocks, or one or more CSI-RSresources, associated with a CSI-RS resource index (CRI), or one or moreDM-RSs of PBCH, may be used as RS for measuring quality of a beam pairlink. Quality of a beam pair link may be defined as a reference signalreceived power (RSRP) value, or a reference signal received quality(RSRQ) value, and/or a CSI value measured on RS resources. The basestation may indicate whether an RS resource, used for measuring a beampair link quality, is quasi-co-located (QCLed) with DM-RSs of a controlchannel A RS resource and DM-RSs of a control channel may be calledQCLed when a channel characteristics from a transmission on an RS to awireless device, and that from a transmission on a control channel to awireless device, are similar or same under a configured criterion. In amulti-beam operation, a wireless device may perform an uplink beamsweeping to access a cell.

In an example, a wireless device may be configured to monitor PDCCH onone or more beam pair links simultaneously depending on a capability ofa wireless device. This may increase robustness against beam pair linkblocking. A base station may transmit one or more messages to configurea wireless device to monitor PDCCH on one or more beam pair links indifferent PDCCH OFDM symbols. For example, a base station may transmithigher layer signaling (e.g. RRC signaling) or MAC CE comprisingparameters related to the Rx beam setting of a wireless device formonitoring PDCCH on one or more beam pair links. A base station maytransmit indication of spatial QCL assumption between a DL RS antennaport(s) (for example, cell-specific CSI-RS, or wireless device-specificCSI-RS, or SS block, or PBCH with or without DM-RSs of PBCH), and DL RSantenna port(s) for demodulation of DL control channel. Signaling forbeam indication for a PDCCH may be MAC CE signaling, or RRC signaling,or DCI signaling, or specification-transparent and/or implicit method,and combination of these signaling methods.

For reception of unicast DL data channel, a base station may indicatespatial QCL parameters between DL RS antenna port(s) and DM-RS antennaport(s) of DL data channel The base station may transmit DCI (e.g.downlink grants) comprising information indicating the RS antennaport(s). The information may indicate RS antenna port(s) which may beQCL-ed with the DM-RS antenna port(s). Different set of DM-RS antennaport(s) for a DL data channel may be indicated as QCL with different setof the RS antenna port(s).

FIG. 9A and FIG. 9B show packet flows employing a multi connectivity(e.g. dual connectivity, multi connectivity, tight interworking, and/orthe like). FIG. 9A is an example diagram of a protocol structure of awireless device 110 (e.g. UE) with CA and/or multi connectivity as peran aspect of an embodiment. FIG. 9B is an example diagram of a protocolstructure of multiple base stations with CA and/or multi connectivity asper an aspect of an embodiment. The multiple base stations may comprisea master node, MN 1130 (e.g. a master node, a master base station, amaster gNB, a master eNB, and/or the like) and a secondary node, SN 1150(e.g. a secondary node, a secondary base station, a secondary gNB, asecondary eNB, and/or the like). A master node 1130 and a secondary node1150 may co-work to communicate with a wireless device 110.

When multi connectivity is configured for a wireless device 110, thewireless device 110, which may support multiple reception/transmissionfunctions in an RRC connected state, may be configured to utilize radioresources provided by multiple schedulers of a multiple base stations.Multiple base stations may be inter-connected via a non-ideal or idealbackhaul (e.g. Xn interface, X2 interface, and/or the like). A basestation involved in multi connectivity for a certain wireless device mayperform at least one of two different roles: a base station may eitheract as a master base station or as a secondary base station. In multiconnectivity, a wireless device may be connected to one master basestation and one or more secondary base stations. In an example, a masterbase station (e.g. the MN 1130) may provide a master cell group (MCG)comprising a primary cell and/or one or more secondary cells for awireless device (e.g. the wireless device 110). A secondary base station(e.g. the SN 1150) may provide a secondary cell group (SCG) comprising aprimary secondary cell (PSCell) and/or one or more secondary cells for awireless device (e.g. the wireless device 110).

In multi connectivity, a radio protocol architecture that a beareremploys may depend on how a bearer is setup. In an example, threedifferent type of bearer setup options may be supported: an MCG bearer,an SCG bearer, and/or a split bearer. A wireless device mayreceive/transmit packets of an MCG bearer via one or more cells of theMCG, and/or may receive/transmits packets of an SCG bearer via one ormore cells of an SCG. Multi-connectivity may also be described as havingat least one bearer configured to use radio resources provided by thesecondary base station. Multi-connectivity may or may not beconfigured/implemented in some of the example embodiments.

In an example, a wireless device (e.g. Wireless Device 110) may transmitand/or receive: packets of an MCG bearer via an SDAP layer (e.g. SDAP1110), a PDCP layer (e.g. NR PDCP 1111), an RLC layer (e.g. MN RLC1114), and a MAC layer (e.g. MN MAC 1118); packets of a split bearer viaan SDAP layer (e.g. SDAP 1110), a PDCP layer (e.g. NR PDCP 1112), one ofa master or secondary RLC layer (e.g. MN RLC 1115, SN RLC 1116), and oneof a master or secondary MAC layer (e.g. MN MAC 1118, SN MAC 1119);and/or packets of an SCG bearer via an SDAP layer (e.g. SDAP 1110), aPDCP layer (e.g. NR PDCP 1113), an RLC layer (e.g. SN RLC 1117), and aMAC layer (e.g. MN MAC 1119).

In an example, a master base station (e.g. MN 1130) and/or a secondarybase station (e.g. SN 1150) may transmit/receive: packets of an MCGbearer via a master or secondary node SDAP layer (e.g. SDAP 1120, SDAP1140), a master or secondary node PDCP layer (e.g. NR PDCP 1121, NR PDCP1142), a master node RLC layer (e.g. MN RLC 1124, MN RLC 1125), and amaster node MAC layer (e.g. MN MAC 1128); packets of an SCG bearer via amaster or secondary node SDAP layer (e.g. SDAP 1120, SDAP 1140), amaster or secondary node PDCP layer (e.g. NR PDCP 1122, NR PDCP 1143), asecondary node RLC layer (e.g. SN RLC 1146, SN RLC 1147), and asecondary node MAC layer (e.g. SN MAC 1148); packets of a split bearervia a master or secondary node SDAP layer (e.g. SDAP 1120, SDAP 1140), amaster or secondary node PDCP layer (e.g. NR PDCP 1123, NR PDCP 1141), amaster or secondary node RLC layer (e.g. MN RLC 1126, SN RLC 1144, SNRLC 1145, MN RLC 1127), and a master or secondary node MAC layer (e.g.MN MAC 1128, SN MAC 1148).

In multi connectivity, a wireless device may configure multiple MACentities: one MAC entity (e.g. MN MAC 1118) for a master base station,and other MAC entities (e.g. SN MAC 1119) for a secondary base station.In multi-connectivity, a configured set of serving cells for a wirelessdevice may comprise two subsets: an MCG comprising serving cells of amaster base station, and SCGs comprising serving cells of a secondarybase station. For an SCG, one or more of following configurations may beapplied: at least one cell of an SCG has a configured UL CC and at leastone cell of a SCG, named as primary secondary cell (PSCell, PCell ofSCG, or sometimes called PCell), is configured with PUCCH resources;when an SCG is configured, there may be at least one SCG bearer or oneSplit bearer; upon detection of a physical layer problem or a randomaccess problem on a PSCell, or a number of NR RLC retransmissions hasbeen reached associated with the SCG, or upon detection of an accessproblem on a PSCell during a SCG addition or a SCG change: an RRCconnection re-establishment procedure may not be triggered, ULtransmissions towards cells of an SCG may be stopped, a master basestation may be informed by a wireless device of a SCG failure type, forsplit bearer, a DL data transfer over a master base station may bemaintained; an NR RLC acknowledged mode (AM) bearer may be configuredfor a split bearer; PCell and/or PSCell may not be de-activated; PS Cellmay be changed with a SCG change procedure (e.g. with security keychange and a RACH procedure); and/or a bearer type change between asplit bearer and a SCG bearer or simultaneous configuration of a SCG anda split bearer may or may not supported.

With respect to interaction between a master base station and asecondary base stations for multi-connectivity, one or more of thefollowing may be applied: a master base station and/or a secondary basestation may maintain RRM measurement configurations of a wirelessdevice; a master base station may (e.g. based on received measurementreports, traffic conditions, and/or bearer types) may decide to requesta secondary base station to provide additional resources (e.g. servingcells) for a wireless device; upon receiving a request from a masterbase station, a secondary base station may create/modify a containerthat may result in configuration of additional serving cells for awireless device (or decide that the secondary base station has noresource available to do so); for a UE capability coordination, a masterbase station may provide (a part of) an AS configuration and UEcapabilities to a secondary base station; a master base station and asecondary base station may exchange information about a UE configurationby employing of RRC containers (inter-node messages) carried via Xnmessages; a secondary base station may initiate a reconfiguration of thesecondary base station existing serving cells (e.g. PUCCH towards thesecondary base station); a secondary base station may decide which cellis a PSCell within a SCG; a master base station may or may not changecontent of RRC configurations provided by a secondary base station; incase of a SCG addition and/or a SCG SCell addition, a master basestation may provide recent (or the latest) measurement results for SCGcell(s); a master base station and secondary base stations may receiveinformation of SFN and/or subframe offset of each other from OAM and/orvia an Xn interface, (e.g. for a purpose of DRX alignment and/oridentification of a measurement gap). In an example, when adding a newSCG SCell, dedicated RRC signaling may be used for sending requiredsystem information of a cell as for CA, except for a SFN acquired from aMIB of a PSCell of a SCG.

FIG. 10 is an example diagram of a random access procedure. One or moreevents may trigger a random access procedure. For example, one or moreevents may be at least one of following: initial access from RRC_IDLE,RRC connection re-establishment procedure, handover, DL or UL dataarrival during RRC_CONNECTED when UL synchronization status isnon-synchronized, transition from RRC_Inactive, and/or request for othersystem information. For example, a PDCCH order, a MAC entity, and/or abeam failure indication may initiate a random access procedure.

In an example embodiment, a random access procedure may be at least oneof a contention based random access procedure and a contention freerandom access procedure. For example, a contention based random accessprocedure may comprise, one or more Msg 1 1220 transmissions, one ormore Msg2 1230 transmissions, one or more Msg3 1240 transmissions, andcontention resolution 1250. For example, a contention free random accessprocedure may comprise one or more Msg 1 1220 transmissions and one ormore Msg2 1230 transmissions.

In an example, a base station may transmit (e.g., unicast, multicast, orbroadcast), to a UE, a RACH configuration 1210 via one or more beams.The RACH configuration 1210 may comprise one or more parametersindicating at least one of following: available set of PRACH resourcesfor a transmission of a random access preamble, initial preamble power(e.g., random access preamble initial received target power), an RSRPthreshold for a selection of a SS block and corresponding PRACHresource, a power-ramping factor (e.g., random access preamble powerramping step), random access preamble index, a maximum number ofpreamble transmission, preamble group A and group B, a threshold (e.g.,message size) to determine the groups of random access preambles, a setof one or more random access preambles for system information requestand corresponding PRACH resource(s), if any, a set of one or more randomaccess preambles for beam failure recovery request and correspondingPRACH resource(s), if any, a time window to monitor RA response(s), atime window to monitor response(s) on beam failure recovery request,and/or a contention resolution timer.

In an example, the Msg 1 1220 may be one or more transmissions of arandom access preamble. For a contention based random access procedure,a UE may select a SS block with a RSRP above the RSRP threshold. Ifrandom access preambles group B exists, a UE may select one or morerandom access preambles from a group A or a group B depending on apotential Msg3 1240 size. If a random access preambles group B does notexist, a UE may select the one or more random access preambles from agroup A. A UE may select a random access preamble index randomly (e.g.with equal probability or a normal distribution) from one or more randomaccess preambles associated with a selected group. If a base stationsemi-statistically configures a UE with an association between randomaccess preambles and SS blocks, the UE may select a random accesspreamble index randomly with equal probability from one or more randomaccess preambles associated with a selected SS block and a selectedgroup.

For example, a UE may initiate a contention free random access procedurebased on a beam failure indication from a lower layer. For example, abase station may semi-statistically configure a UE with one or morecontention free PRACH resources for beam failure recovery requestassociated with at least one of SS blocks and/or CSI-RSs. If at leastone of SS blocks with a RSRP above a first RSRP threshold amongstassociated SS blocks or at least one of CSI-RSs with a RSRP above asecond RSRP threshold amongst associated CSI-RSs is available, a UE mayselect a random access preamble index corresponding to a selected SSblock or CSI-RS from a set of one or more random access preambles forbeam failure recovery request.

For example, a UE may receive, from a base station, a random accesspreamble index via PDCCH or RRC for a contention free random accessprocedure. If a base station does not configure a UE with at least onecontention free PRACH resource associated with SS blocks or CSI-RS, theUE may select a random access preamble index. If a base stationconfigures a UE with one or more contention free PRACH resourcesassociated with SS blocks and at least one SS block with a RSRP above afirst RSRP threshold amongst associated SS blocks is available, the UEmay select the at least one SS block and select a random access preamblecorresponding to the at least one SS block. If a base station configuresa UE with one or more contention free PRACH resources associated withCSI-RSs and at least one CSI-RS with a RSRP above a second RSPRthreshold amongst the associated CSI-RSs is available, the UE may selectthe at least one CSI-RS and select a random access preamblecorresponding to the at least one CSI-RS.

A UE may perform one or more Msg1 1220 transmissions by transmitting theselected random access preamble. For example, if a UE selects an SSblock and is configured with an association between one or more PRACHoccasions and one or more SS blocks, the UE may determine a PRACHoccasion from one or more PRACH occasions corresponding to a selected SSblock. For example, if a UE selects a CSI-RS and is configured with anassociation between one or more PRACH occasions and one or more CSI-RSs,the UE may determine a PRACH occasion from one or more PRACH occasionscorresponding to a selected CSI-RS. A UE may transmit, to a basestation, a selected random access preamble via a selected PRACHoccasions. A UE may determine a transmit power for a transmission of aselected random access preamble at least based on an initial preamblepower and a power-ramping factor. A UE may determine a RA-RNTIassociated with a selected PRACH occasions in which a selected randomaccess preamble is transmitted. For example, a UE may not determine aRA-RNTI for a beam failure recovery request. A UE may determine anRA-RNTI at least based on an index of a first OFDM symbol and an indexof a first slot of a selected PRACH occasions, and/or an uplink carrierindex for a transmission of Msg 1 1220.

In an example, a UE may receive, from a base station, a random accessresponse, Msg 2 1230. A UE may start a time window (e.g., ra-ResponseWindow) to monitor a random access response. For beam failure recoveryrequest, a base station may configure a UE with a different time window(e.g., bfr-Response Window) to monitor response on beam failure recoveryrequest. For example, a UE may start a time window (e.g.,ra-ResponseWindow or bfr-Response Window) at a start of a first PDCCHoccasion after a fixed duration of one or more symbols from an end of apreamble transmission. If a UE transmits multiple preambles, the UE maystart a time window at a start of a first PDCCH occasion after a fixedduration of one or more symbols from an end of a first preambletransmission. A UE may monitor a PDCCH of a cell for at least one randomaccess response identified by a RA-RNTI or for at least one response tobeam failure recovery request identified by a C-RNTI while a timer for atime window is running

In an example, a UE may consider a reception of random access responsesuccessful if at least one random access response comprises a randomaccess preamble identifier corresponding to a random access preambletransmitted by the UE. A UE may consider the contention free randomaccess procedure successfully completed if a reception of random accessresponse is successful. If a contention free random access procedure istriggered for a beam failure recovery request, a UE may consider acontention free random access procedure successfully complete if a PDCCHtransmission is addressed to a C-RNTI. In an example, if at least onerandom access response comprises a random access preamble identifier, aUE may consider the random access procedure successfully completed andmay indicate a reception of an acknowledgement for a system informationrequest to upper layers. If a UE has signaled multiple preambletransmissions, the UE may stop transmitting remaining preambles (if any)in response to a successful reception of a corresponding random accessresponse.

In an example, a UE may perform one or more Msg 3 1240 transmissions inresponse to a successful reception of random access response (e.g., fora contention based random access procedure). A UE may adjust an uplinktransmission timing based on a timing advanced command indicated by arandom access response and may transmit one or more transport blocksbased on an uplink grant indicated by a random access response.Subcarrier spacing for PUSCH transmission for Msg3 1240 may be providedby at least one higher layer (e.g. RRC) parameter. A UE may transmit arandom access preamble via PRACH and Msg3 1240 via PUSCH on a same cell.A base station may indicate an UL BWP for a PUSCH transmission of Msg31240 via system information block. A UE may employ HARQ for aretransmission of Msg 3 1240.

In an example, multiple UEs may perform Msg 1 1220 by transmitting asame preamble to a base station and receive, from the base station, asame random access response comprising an identity (e.g., TC-RNTI).Contention resolution 1250 may ensure that a UE does not incorrectly usean identity of another UE. For example, contention resolution 1250 maybe based on C-RNTI on PDCCH or a UE contention resolution identity onDL-SCH. For example, if a base station assigns a C-RNTI to a UE, the UEmay perform contention resolution 1250 based on a reception of a PDCCHtransmission that is addressed to the C-RNTI. In response to detectionof a C-RNTI on a PDCCH, a UE may consider contention resolution 1250successful and may consider a random access procedure successfullycompleted. If a UE has no valid C-RNTI, a contention resolution may beaddressed by employing a TC-RNTI. For example, if a MAC PDU issuccessfully decoded and a MAC PDU comprises a UE contention resolutionidentity MAC CE that matches the CCCH SDU transmitted in Msg3 1250, a UEmay consider the contention resolution 1250 successful and may considerthe random access procedure successfully completed.

FIG. 11 is an example structure for MAC entities as per an aspect of anembodiment. In an example, a wireless device may be configured tooperate in a multi-connectivity mode. A wireless device in RRC_CONNECTEDwith multiple RX/TX may be configured to utilize radio resourcesprovided by multiple schedulers located in a plurality of base stations.The plurality of base stations may be connected via a non-ideal or idealbackhaul over the Xn interface. In an example, a base station in aplurality of base stations may act as a master base station or as asecondary base station. A wireless device may be connected to one masterbase station and one or more secondary base stations. A wireless devicemay be configured with multiple MAC entities, e.g. one MAC entity formaster base station, and one or more other MAC entities for secondarybase station(s). In an example, a configured set of serving cells for awireless device may comprise two subsets: an MCG comprising servingcells of a master base station, and one or more SCGs comprising servingcells of a secondary base station(s). FIG. 13 illustrates an examplestructure for MAC entities when MCG and SCG are configured for awireless device.

In an example, at least one cell in a SCG may have a configured UL CC,wherein a cell of at least one cell may be called PSCell or PCell ofSCG, or sometimes may be simply called PCell. A PSCell may be configuredwith PUCCH resources. In an example, when a SCG is configured, there maybe at least one SCG bearer or one split bearer. In an example, upondetection of a physical layer problem or a random access problem on aPSCell, or upon reaching a number of RLC retransmissions associated withthe SCG, or upon detection of an access problem on a PSCell during a SCGaddition or a SCG change: an RRC connection re-establishment proceduremay not be triggered, UL transmissions towards cells of an SCG may bestopped, a master base station may be informed by a UE of a SCG failuretype and DL data transfer over a master base station may be maintained.

In an example, a MAC sublayer may provide services such as data transferand radio resource allocation to upper layers (e.g. 1310 or 1320). A MACsublayer may comprise a plurality of MAC entities (e.g. 1350 and 1360).A MAC sublayer may provide data transfer services on logical channels.To accommodate different kinds of data transfer services, multiple typesof logical channels may be defined. A logical channel may supporttransfer of a particular type of information. A logical channel type maybe defined by what type of information (e.g., control or data) istransferred. For example, BCCH, PCCH, CCCH and DCCH may be controlchannels and DTCH may be a traffic channel. In an example, a first MACentity (e.g. 1310) may provide services on PCCH, BCCH, CCCH, DCCH, DTCHand MAC control elements. In an example, a second MAC entity (e.g. 1320)may provide services on BCCH, DCCH, DTCH and MAC control elements.

A MAC sublayer may expect from a physical layer (e.g. 1330 or 1340)services such as data transfer services, signaling of HARQ feedback,signaling of scheduling request or measurements (e.g. CQI). In anexample, in dual connectivity, two MAC entities may be configured for awireless device: one for MCG and one for SCG. A MAC entity of wirelessdevice may handle a plurality of transport channels. In an example, afirst MAC entity may handle first transport channels comprising a PCCHof MCG, a first BCH of MCG, one or more first DL-SCHs of MCG, one ormore first UL-SCHs of MCG and one or more first RACHs of MCG. In anexample, a second MAC entity may handle second transport channelscomprising a second BCH of SCG, one or more second DL-SCHs of SCG, oneor more second UL-SCHs of SCG and one or more second RACHs of SCG.

In an example, if a MAC entity is configured with one or more SCells,there may be multiple DL-SCHs and there may be multiple UL-SCHs as wellas multiple RACHs per MAC entity. In an example, there may be one DL-SCHand UL-SCH on a SpCell. In an example, there may be one DL-SCH, zero orone UL-SCH and zero or one RACH for an SCell. A DL-SCH may supportreceptions using different numerologies and/or TTI duration within a MACentity. A UL-SCH may also support transmissions using differentnumerologies and/or TTI duration within the MAC entity.

In an example, a MAC sublayer may support different functions and maycontrol these functions with a control (e.g. 1355 or 1365) element.Functions performed by a MAC entity may comprise mapping between logicalchannels and transport channels (e.g., in uplink or downlink),multiplexing (e.g. 1352 or 1362) of MAC SDUs from one or differentlogical channels onto transport blocks (TB) to be delivered to thephysical layer on transport channels (e.g., in uplink), demultiplexing(e.g. 1352 or 1362) of MAC SDUs to one or different logical channelsfrom transport blocks (TB) delivered from the physical layer ontransport channels (e.g., in downlink), scheduling information reporting(e.g., in uplink), error correction through HARQ in uplink or downlink(e.g. 1363), and logical channel prioritization in uplink (e.g. 1351 or1361). A MAC entity may handle a random access process (e.g. 1354 or1364).

FIG. 12 is an example diagram of a RAN architecture comprising one ormore base stations. In an example, a protocol stack (e.g. RRC, SDAP,PDCP, RLC, MAC, and PHY) may be supported at a node. A base station(e.g. 120A or 120B) may comprise a base station central unit (CU) (e.g.gNB-CU 1420A or 1420B) and at least one base station distributed unit(DU) (e.g. gNB-DU 1430A, 1430B, 1430C, or 1430D) if a functional splitis configured. Upper protocol layers of a base station may be located ina base station CU, and lower layers of the base station may be locatedin the base station DUs. An Fl interface (e.g. CU-DU interface)connecting a base station CU and base station DUs may be an ideal ornon-ideal backhaul. F1-C may provide a control plane connection over anF1 interface, and F1-U may provide a user plane connection over the F1interface. In an example, an Xn interface may be configured between basestation CUs.

In an example, a base station CU may comprise an RRC function, an SDAPlayer, and a PDCP layer, and base station DUs may comprise an RLC layer,a MAC layer, and a PHY layer. In an example, various functional splitoptions between a base station CU and base station DUs may be possibleby locating different combinations of upper protocol layers (RANfunctions) in a base station CU and different combinations of lowerprotocol layers (RAN functions) in base station DUs. A functional splitmay support flexibility to move protocol layers between a base stationCU and base station DUs depending on service requirements and/or networkenvironments.

In an example, functional split options may be configured per basestation, per base station CU, per base station DU, per UE, per bearer,per slice, or with other granularities. In per base station CU split, abase station CU may have a fixed split option, and base station DUs maybe configured to match a split option of a base station CU. In per basestation DU split, a base station DU may be configured with a differentsplit option, and a base station CU may provide different split optionsfor different base station DUs. In per UE split, a base station (basestation CU and at least one base station DUs) may provide differentsplit options for different wireless devices. In per bearer split,different split options may be utilized for different bearers. In perslice splice, different split options may be applied for differentslices.

FIG. 13 is an example diagram showing RRC state transitions of awireless device. In an example, a wireless device may be in at least oneRRC state among an RRC connected state (e.g. RRC Connected 1530,RRC_Connected), an RRC idle state (e.g. RRC Idle 1510, RRC_Idle), and/oran RRC inactive state (e.g. RRC Inactive 1520, RRC_Inactive). In anexample, in an RRC connected state, a wireless device may have at leastone RRC connection with at least one base station (e.g. gNB and/or eNB),which may have a UE context of the wireless device. A UE context (e.g. awireless device context) may comprise at least one of an access stratumcontext, one or more radio link configuration parameters, bearer (e.g.data radio bearer (DRB), signaling radio bearer (SRB), logical channel,QoS flow, PDU session, and/or the like) configuration information,security information, PHY/MAC/RLC/PDCP/SDAP layer configurationinformation, and/or the like configuration information for a wirelessdevice. In an example, in an RRC idle state, a wireless device may nothave an RRC connection with a base station, and a UE context of awireless device may not be stored in a base station. In an example, inan RRC inactive state, a wireless device may not have an RRC connectionwith a base station. A UE context of a wireless device may be stored ina base station, which may be called as an anchor base station (e.g. lastserving base station).

In an example, a wireless device may transition a UE RRC state betweenan RRC idle state and an RRC connected state in both ways (e.g.connection release 1540 or connection establishment 1550; or connectionreestablishment) and/or between an RRC inactive state and an RRCconnected state in both ways (e.g. connection inactivation 1570 orconnection resume 1580). In an example, a wireless device may transitionits RRC state from an RRC inactive state to an RRC idle state (e.g.connection release 1560).

In an example, an anchor base station may be a base station that maykeep a UE context (a wireless device context) of a wireless device atleast during a time period that a wireless device stays in a RANnotification area (RNA) of an anchor base station, and/or that awireless device stays in an RRC inactive state. In an example, an anchorbase station may be a base station that a wireless device in an RRCinactive state was lastly connected to in a latest RRC connected stateor that a wireless device lastly performed an RNA update procedure in.In an example, an RNA may comprise one or more cells operated by one ormore base stations. In an example, a base station may belong to one ormore RNAs. In an example, a cell may belong to one or more RNAs.

In an example, a wireless device may transition a UE RRC state from anRRC connected state to an RRC inactive state in a base station. Awireless device may receive RNA information from the base station. RNAinformation may comprise at least one of an RNA identifier, one or morecell identifiers of one or more cells of an RNA, a base stationidentifier, an IP address of the base station, an AS context identifierof the wireless device, a resume identifier, and/or the like.

In an example, an anchor base station may broadcast a message (e.g. RANpaging message) to base stations of an RNA to reach to a wireless devicein an RRC inactive state, and/or the base stations receiving the messagefrom the anchor base station may broadcast and/or multicast anothermessage (e.g. paging message) to wireless devices in their coveragearea, cell coverage area, and/or beam coverage area associated with theRNA through an air interface.

In an example, when a wireless device in an RRC inactive state movesinto a new RNA, the wireless device may perform an RNA update (RNAU)procedure, which may comprise a random access procedure by the wirelessdevice and/or a UE context retrieve procedure. A UE context retrieve maycomprise: receiving, by a base station from a wireless device, a randomaccess preamble; and fetching, by a base station, a UE context of thewireless device from an old anchor base station. Fetching may comprise:sending a retrieve UE context request message comprising a resumeidentifier to the old anchor base station and receiving a retrieve UEcontext response message comprising the UE context of the wirelessdevice from the old anchor base station.

In an example embodiment, a wireless device in an RRC inactive state mayselect a cell to camp on based on at least a measurement result for oneor more cells, a cell where a wireless device may monitor an RNA pagingmessage and/or a core network paging message from a base station. In anexample, a wireless device in an RRC inactive state may select a cell toperform a random access procedure to resume an RRC connection and/or totransmit one or more packets to a base station (e.g. to a network). Inan example, if a cell selected belongs to a different RNA from an RNAfor a wireless device in an RRC inactive state, the wireless device mayinitiate a random access procedure to perform an RNA update procedure.In an example, if a wireless device in an RRC inactive state has one ormore packets, in a buffer, to transmit to a network, the wireless devicemay initiate a random access procedure to transmit one or more packetsto a base station of a cell that the wireless device selects. A randomaccess procedure may be performed with two messages (e.g. 2 stage randomaccess) and/or four messages (e.g. -k -b 4 stage random access) betweenthe wireless device and the base station.

In an example embodiment, a base station receiving one or more uplinkpackets from a wireless device in an RRC inactive state may fetch a UEcontext of a wireless device by transmitting a retrieve UE contextrequest message for the wireless device to an anchor base station of thewireless device based on at least one of an AS context identifier, anRNA identifier, a base station identifier, a resume identifier, and/or acell identifier received from the wireless device. In response tofetching a UE context, a base station may transmit a path switch requestfor a wireless device to a core network entity (e.g. AMF, MME, and/orthe like). A core network entity may update a downlink tunnel endpointidentifier for one or more bearers established for the wireless devicebetween a user plane core network entity (e.g. UPF, S-GW, and/or thelike) and a RAN node (e.g. the base station), e g changing a downlinktunnel endpoint identifier from an address of the anchor base station toan address of the base station.

A gNB may communicate with a wireless device via a wireless networkemploying one or more new radio technologies. The one or more radiotechnologies may comprise at least one of: multiple technologies relatedto physical layer; multiple technologies related to medium accesscontrol layer; and/or multiple technologies related to radio resourcecontrol layer. Example embodiments of enhancing the one or more radiotechnologies may improve performance of a wireless network. Exampleembodiments may increase the system throughput, or data rate oftransmission. Example embodiments may reduce battery consumption of awireless device. Example embodiments may improve latency of datatransmission between a gNB and a wireless device. Example embodimentsmay improve network coverage of a wireless network. Example embodimentsmay improve transmission efficiency of a wireless network.

In an example embodiment, a wireless device of the 5G network may stayin at least one RRC state among an RRC connected state, an RRC idlestate, and an RRC inactive state. In an example, in an RRC connectedstate, a wireless device may have at least one RRC connection with atleast one base station, which may have a UE context of the wirelessdevice. A UE context (a wireless device context) may comprise at leastone of an AS context, a bearer configuration information, a securityinformation, a PDCP configuration information, and/or otherconfiguration information for a wireless device. In an example, in anRRC idle state, a wireless device may not have a RRC connection with abase station, and a UE context of a wireless device may not be stored ina base station. In an example, in an RRC inactive state, a wirelessdevice may not have a RRC connection with a base station, but a UEcontext of a wireless device may be stored in a base station, which maybe called as an anchor base station.

In an example embodiment, a wireless device may transition its RRC statebetween an RRC idle state and an RRC connected state in both ways, andbetween an RRC inactive state and an RRC connected state in both ways,and from an RRC inactive state to an RRC idle state in one direction.

In an example embodiment, an anchor base station may be a base stationthat may keep a UE context (a wireless device context) at least as longas a wireless device associated of the UE context stays in an RNA (RANnotification area) of the anchor base station. In an example, an anchorbase station, in a UE specific anchor case, may be a base station that awireless device in an RRC inactive state was lastly connected to in thelatest RRC connected state or that a wireless device lastly performed aRNA update procedure in. In an example, an anchor base station, in acommon anchor case, may be a base station determined to keep UE contextsof wireless devices in an RRC inactive state staying in an RNA of theanchor base station. In common anchor case, one or more anchor basestations may exist in an RNA.

In an example embodiment, an RNA may comprise one or more cells operatedby one or more base stations. In an example, a base station may belongto one or more RNAs. In an example, a cell may belong to one or moreRNAs. In an example, an anchor base station may broadcast a message tobase stations in an RNA to reach to a wireless device in an RRC inactivestate, and base stations receiving a broadcasted message from an anchorbase station may broadcast and/or multicast another message to wirelessdevices in their coverage area, cell coverage area, and/or beam coveragearea associated with the RNA through an air interface. In an example,when a wireless device in an RRC inactive state moves into a new RNA, itmay perform an RNA update (RNAU) procedure, which may comprise a randomaccess procedure by the wireless device and/or a UE context retrieveprocedure, by a base station receiving a random access preamble messagefrom the wireless device, fetching a UE context of the wireless devicefrom an old anchor base station of an old RNA to a new anchor basestation of the new RNA.

In an example embodiment, a wireless device may transition its RRC statefrom an RRC connected state to an RRC inactive state in a first basestation. In an example, the wireless device may receive an RNAinformation from the first base station. In case that the first basestation is an anchor base station for the wireless device (i.e. in a UEspecific anchor case or if the first base station is an anchor basestation in a common anchor case), the RNA information may comprise atleast one of an RNA identifier, a cell identifier, a base stationidentifier, an IP address of the first base station, and/or an AScontext identifier of the wireless device. In case that the first basestation is not an anchor base station for the wireless device (i.e. ifthe first base station is not an anchor base station in a common anchorcase), the RNA information may comprise at least one of an RNAidentifier, a cell identifier of the first base station, a base stationidentifier of an anchor base station, an IP address of an anchor basestation, and/or an AS context identifier.

In an example, in case that the first base station is an anchor basestation for the wireless device, the first base station may keep a UEcontext of the wireless device at least during a period when thewireless device stays in an RNA associated with the wireless device. Incase that the first base station is not an anchor base station for thewireless device, the first base station may transfer one or moreelements of a UE context of the wireless device to an anchor basestation, and the anchor base station may keep one or more elements ofthe UE context of the wireless device at least during a period when thewireless device stays in an RNA associated with the wireless device.

In an example embodiment, a wireless device in an RRC inactive state mayselect a cell where the wireless device receives an RNA paging messageand/or a core network paging message from a base station. In an example,a wireless device in an RRC inactive state may select a cell to performa random access procedure to establish an RRC connection and/or totransmit one or more packets. In an example, if the selected cellbelongs to a different RNA than an RNA associated with the wirelessdevice, the wireless device may initiate a random access procedure toperform an RNA update procedure. In an example, if a wireless device inan RRC inactive state has one or more packets, in its buffer, totransmit to the network, the wireless device may initiate a randomaccess procedure to transmit the one or more packets to a base stationof a cell that the wireless device selected. The random access proceduremay be performed with two messages and/or four messages between thewireless device and the base station. In an example, one or more uplinkpackets of a wireless device in an RRC inactive state may be PDCPprotocol layer packets.

In an example embodiment, one or more uplink packets from a wirelessdevice in an RRC inactive state may be transmitted to a core networkentity. In an example, a first base station receiving one or more uplinkpackets from a wireless device in an RRC inactive state may transmit theone or more uplink packets to an anchor base station of the wirelessdevice based on at least one of an AS context identifier, an RNAidentifier, a base station identifier, and/or a cell identifier receivedfrom the wireless device. In an example, the anchor base station maytransmit the uplink data packets to a core network entity at least basedon a UE context retrieved at least based on an AS context identifierand/or a wireless device identifier received from the first basestation.

In an example embodiment, a first base station receiving one or moreuplink packets from a wireless device in an RRC inactive state maytransmit a UE context fetch request for the wireless device to an anchorbase station of the wireless device based on at least one of an AScontext identifier, an RNA identifier, a base station identifier, and/ora cell identifier received from the wireless device. In an example, theanchor base station may transmit a UE context for the wireless device tothe first base station based on at least one of an AS context identifierand/or a wireless device identifier received from the first basestation. The first base station receiving the UE context may transmit apath switch request for the wireless device to a core network entity,and the core network entity may update a downlink tunnel endpointidentifier for one or more bearers established for the wireless devicebetween a user plane core network entity and a RAN node, e g changing adownlink tunnel endpoint identifier from an address of the anchor basestation to an address of the first base station. In an example, thefirst base station may transmit the one or more uplink packets to theuser plane core network entity based on at least one of the UE contextand/or the updated one or more bearers between the user plane corenetwork entity and the first base station. In an example, the anchorbase station may remove the UE context for the wireless device.

In addition to the CN tracking areas, a UE in RRC_INACTIVE may betracked on a “RAN based notification area” (called “RAN area” herein)wherein the UE may move freely without notifying the network. Once theUE moves outside the RAN area, it may perform a RAN area update.

As the RAN areas are only applicable to UEs in RRC_INACTIVE, the RANarea updates may be performed with the RRCConnectionResumeRequestmessage (e.g. the message may be used to transition from RRC_INACTIVE toRRC_CONNECTED) with a causeValue equal to e.g.“ranNotificationAreaUpdateRequest”. The motivation for using thismessage may be that there may be DL data waiting so the network may havethe possibility to order the UE to RRC_CONNECTED (and complete the“resume” procedure).

When the network receives the RRCConnectionResumeRequest message, if itfinds the UE context, it may relocate the UE context and the CN/RANconnection and then directly may suspend the UE with an updated RANnotification Area using the RRCConnectionSuspend message. If there areDL data for the UE at this point, the network may respond with anRRCConnectionResume message transitioning the UE to RRC_CONNECTED. Ifthere is no UL or DL data, the UE may return to RRC_INACTIVE as soon aspossible. The UE may need to be given a new resume Identity when it issuspended to RRC_INACTIVE in order to indicate the new location of theUE context. The UE specific RAN area may be updated with theranAreaInformation included in the RRCConnectionSuspend message. TheranAreaInformation may either indicate the entire new RAN area using alist of cells, or use delta-signalling to inform which cells may beadded/removed from the RAN area. In addition, the ranAreaInformation mayalso indicate whether the UE may use its old RAN area, or if the RANarea may consist of the UE's TAI-list.

Since the UE may be assigned with a new RAN area and a new Resume ID(resume identity) when the connection is suspended it may be importantthat the RRCConnectionSuspend message may be encrypted and integrityprotected. In LTE, this may be achieved by providing the UE with theNext Hop Chaining Counter (NCC) in the RRCConnectionSetup message andtransition into RRC_CONNECTED where security may be enabled. In order tooptimize the RAN area update procedure, and allow the UE to be directlysuspended to RRC_INACTIVE as a response to theRRCConnectionResumeRequest, it may be necessary that the UE may havealready derived the encryption keys at MSG3. This may be achieved byproviding the UE with the NCC already in the RRCConnectionSuspendmessage. This may also allow for integrity protection of theRRCConnectionResumeRequest.

In addition, there may be cases where the RAN cannot retrieve the old UEcontext, e.g. if it is lost or discarded, or resides in a gNB from whichit cannot fetch the context. In this case, it may not be possible tocomplete the RAN area update without first re-building the RAN context.

In that case, when the UE transmit the RRCConnectionResumeRequestmessage, the RAN may respond with an RRCConnectionSetup which maytrigger the UE to initiate NAS level procedure causing the CN to rebuildthe UE context in the RAN. Since the RAN may be aware that the UE wantedto perform a RAN notification area update, and that there may be no ULor DL data available, it may quickly re-suspend the UE to RRC_INACTIVEonce the AS context has been rebuilt as can be seen in FIG. 3.

If the RAN decides that the UE may not be re-suspended to RRC_INACTIVEafter the RAN Notification Area Update, it may respond with anRRCConnectionReject which may cause the UE to transition to RRC_IDLE.Additional signalling may be needed on the network side to trigger theremoval of the RAN context.

In LTE, a UE in RRC_IDLE may perform periodic TAU (Tracking Area Update)when the TA update timer (T3412) expires in order for the CN toascertain the UE location on a Tracking Area level and to check if UE isstill attached to the network. For instance, if a UE is turned off, theabsence of a periodic TAU may indicate to the CN that the UE may nolonger inside the attached and that the network context may be removed.In RRC_CONNECTED, there may no need to perform the periodic TAU as thenetwork may know the UE location on a cell level and it may be theresponsibility of the RAN layer to ensure UE is still connected. ForRRC_INACTIVE, the motivation to perform periodic area updates may remainthe same as for periodic TAUs in RRC_IDLE, i.e. the network may need tobe able to ascertain that a UE may not disappeared from the network,without informing the network (e.g. power off). The UE in an RRCinactive state may perform periodic TAU, RAN area updates, or both.

As the periodic area updates are mainly intended to inform the networkthat the UE may remain in the same area as before, this signalling maybe performed as lightweight as possible. If a periodic TAU is performedfrom RRC_INACTIVE, the UE may enter RRC_CONNECTED to transmit the NASmessage “TAU Request” and may await the NAS message “TAU Accept” fromthe CN before it may return to RRC_INACTIVE. On the other hand, asuccessful periodic RAN area update may consist of anRRCConnectionResumeRequest message with e.g. a causeValue“ranNotificationAreaUpdateRequest”. If the periodic RAN area update isperformed in same gNB as the UE may have been suspended in, the UEcontext may be already available in the gNB and the UE may directly besuspended to RRC_INACTIVE. The RRCConnectionSuspend message from the gNBmay contain a new resumeId (resume identity), a “ranAreaInformation”(e.g. a cell list, or an indication to use the old RAN area, or anindication to use the TA-list as RAN area), as well as the Next HopChaining Counter (NCC). The new Resume ID (resume identity) may indicatethe updated UE context, the RAN area information may ensure that the UEmay maintain an up-to-date RAN area, while the NCC may ensure that theUE can resume the connection with encryption enabled already in messagethree of random access procedure, even in a different gNB.

If the UE resumes the connection in another gNB inside the RAN area, theUE context may be fetched from the old gNB using similar procedure asfor RAN area updates based on mobility. In addition, the RAN may decideto release the UE to RRC_IDLE during the periodic RAN area update, e.g.if it may have performed multiple periodic RAN area updates within thesame area without any UP activity. If the UE resumes the connection inthe old gNB, the RAN may respond to the RRCConnectionResumeRequest withan RRCConnectionRelease as seen in FIG. 5. When the RAN releases the UEcontext, it may be necessary to inform the CN so that it can release theCN context and/or the UE context stored in another gNB.

The periodic TA update timer (T3412) may be set by the CN and may have adefault value of 54 minutes in LTE. However, in some cases as the RANmay want to have a different periodicity of the periodic location updatethan the periodic TAU. Therefore, the RAN may be able to configure anindependent timer for the RAN area updates. If the periodic RAN areaupdate fails, e.g. if the UE context cannot be retrieved, the RAN maydecide to respond with an RRCConnectionSetup to transition the UE toRRC_CONNECTED so that the CN is also updated as can be seen in FIG. 6.Updating the CN may be important in case the CN thinks the UE may be inRRC_IDLE and may have started the periodic TAU timer.

As the RAN area update may be more lightweight than the TAU, a UE mayonly perform periodic RAN area updates in RRC_INACTIVE.

Example of Inactive State Data Forwarding

In an existing RAN paging procedure, base stations exchanges backhaulsignaling to transmit a downlink packets to a wireless device in an RRCinactive state. An anchor base station may transmit paging messages viaits cells and/or to its neighboring base stations of a RAN notificationarea associated with the wireless device. Implementation of existingbackhaul signaling when a RAN paging procedure is failed may result inincreased packet loss rate and/or increased call drop rate due toinefficient packet forwarding to the wireless device. A failure of a RANpaging procedure may introduce a need for further enhancement incommunication among network nodes (e.g. base stations, core networkentity, and wireless device). In an example, failure rate in receivingdownlink user plane or control plane packets (e.g. data packets, NAS/RRCsignaling packets) may increase for RRC inactive state wireless devices.Increased packet loss rate may degrade network system reliability. Thereis a need to improve backhaul signaling mechanism for RRC inactive statewireless devices. Example embodiments enhance information exchange amongnetwork nodes to improve network communication reliability when awireless device is in an RRC inactive state or an RRC idle state.Example may enhance signaling procedures when a RAN paging procedure isfailed. In an existing network signaling, when a RAN paging procedureinitiated for packet transmissions is failed, an anchor base station maydiscard packets received from a core network entity.

In an example embodiment as shown in FIG. 14 and FIG. 15, when receivingpackets for a wireless device (e.g. UE) in an RRC inactive state from auser plane core network entity (e.g. UPF), a first base station (e.g.gNB) may initiate a RAN paging procedure by transmitting one or morefirst paging messages to one or more second base stations. If the firstbase station fails in the RAN paging procedure, the first base stationmay transmit a paging failure indication to a control plane core networkentity (e.g. AMF). The core network entity may initiate a core networkpaging (e.g. tracking area based paging procedure) for the wirelessdevice. A third base station may receive a response from the wirelessdevice for the core network paging procedure, and the third base stationmay send a tunnel endpoint identifier (e.g. IP address) of the thirdbase station to the first base station, for example, via the corenetwork entity. The first base station may transmit the packets receivedfrom the user plane core network entity to the third base station basedon the tunnel endpoint identifier.

Example embodiments may enhance system reliability by enabling networknodes to share tunnel information for packet forwarding to a wirelessdevice when a RAN paging procedure is failed. Example embodiments mayenable network nodes to reduce packet loss rate or call drop rate for anRRC inactive and/or idle state wireless device in RAN paging failurecases.

In an example, a first base station may receive, from a first corenetwork entity, one or more packets for a wireless device in a radioresource control (RRC) inactive state. The first base station may be ananchor base station of the wireless device, and/or a base station thatinitiated a state transition of the wireless device to an RRC inactivestate. The first base station may keep a UE context of the wirelessdevice. The UE context may comprise at least one of PDU sessionconfigurations, security configurations, radio bearer configurations,logical channel configurations, resume identifier associated with theRRC inactive state, RAN notification area information (e.g. a RAN areaidentifier, a cell identifier, a base station identifier of a RANnotification area of the wireless device). The first core network entitymay comprise a user-plane core network entity (e.g. UPF), acontrol-plane core network entity (e.g. AMF), and/or an applicationserver when the first base station employs a base station-core networkcollocated structure (e.g. selected IP traffic offload, SIPTO). The oneor more packets may comprise downlink data packets for an RRC inactivestate wireless device. In an example, the downlink data packets may beassociated with a certain service, e.g. a vehicle communication downlinkpacket transmission, an ultra reliable low latency (URLLC) service,machine type communication (MTC) services, and/or the like. The one ormore packets may comprise control signaling packets, for example, one ormore NAS layer messages transmitted by the AMF.

In an example, the first base station may initiate a RAN pagingprocedure comprising sending at least one RAN paging message to at leastone second base station. The at least one RAN paging message maycomprise a first identifier of the wireless device. The RAN pagingprocedure may be initiated to page the wireless device being in the RRCinactive state for forwarding the one or more packets received from thefirst core network entity. The at least one paging message may compriseat least one of a UE identifier of the wireless device, a UE pagingidentifier associated with the RAN paging procedure for the wirelessdevice, a paging DRX information for transmission of radio pagingindication to the wireless device (e.g. the at least one second basestation may transmit a paging message via a radio interface based on thepaging DRX information indicating when the wireless device monitorsradio signaling), RAN paging area information of a RAN paging area (e.g.RAN notification area, RAN area identifiers, cell identifiers associatedwith the RAN paging procedure), a RAN paging priority, and/or the like.

In an example, the at least one second base station may serve at leastone cell associated with the RAN paging area (e.g. RAN notificationarea(s), RAN area(s), cell(s)). In an example, when the at least onesecond base station receives the at least one RAN paging message, the atleast one second base station may transmit/broadcast/multicast one ormore paging indications via one or more cells associated with the RANpaging area (e.g. RAN notification area(s), RAN area(s), cell(s)) forthe wireless device. The one or more paging indications may betransmitted via one or more beams of the one or more cells. In anexample, the first base station may transmit the at least one RAN pagingmessage (e.g. RRC paging indication) via its one or more serving cellsassociated with the RAN paging area of the wireless device

In an example, the first base station may determine a failure of the RANpaging procedure in response to not receiving a response of the at leastone RAN paging message. In an example, the first base station maydetermine the failure based on no response for the at least one RANpaging message within a certain time period. When the first base stationreceives a message indicating a UE context retrieve request for thewireless device from at least one of the at least one second basestation in response to the at least one RAN paging message, the firstbase station may consider the RAN paging procedure is successful (e.g.not failed). When the first base station receives a random accesspreamble and/or a RRC connection resume request message from thewireless device in response to the at least one RAN paging message, thefirst base station may consider the RAN paging procedure is successful(e.g. not failed).

In an example, the first base station may send, to a second core networkentity, a first message in response to the failure of the RAN pagingprocedure. In an example, the second core network entity may be acontrol plane core network entity (e.g. AMF). The first message, forexample, may comprise a UE context release request message and/or a RANpaging failure indication message. In an example, the first message mayindicate a RAN paging failure for the wireless device. In an example,the first message may be a UE context release request message comprisinga cause information element indicating that a reason of a UE contextrelease request comprises a failure of a RAN paging procedure for thewireless device.

In an example, the second core network entity may transmit, to one ormore base stations of a tracking area of the wireless device, one ormore core network paging messages (e.g. tracking area paging message) inresponse to the first message. The one or more base station may comprisea third base station. The third message may transmit paging messages viaone or more serving cells of the tracking area, and may receive aresponse for at least one of the paging message from the wirelessdevice. The response may comprise a random access preamble and/or a RRCconnection request/resume message.

In an example, the one or more core network paging messages and/or thepaging messages may comprise an indication parameter indicating that thewireless device is in an RRC inactive state or that a RAN pagingprocedure for the wireless device was failed. In an example, the one ormore core network paging messages and/or the paging messages maycomprise an indication parameter indicating that an anchor base station(e.g. the first base station) has a UE context of the wireless device.In an example, the indication parameter may comprise a resume identifier(ID) of the wireless device for the RRC inactive state. In response toreceiving the response from the wireless device, the third base stationmay transmit a tunnel endpoint identifier (e.g. tunnel identifier) of atunnel for data forwarding to the second core network entity. The dataforwarding may comprise transmitting the one or more packets from thefirst base station to the third base station. The tunnel endpointidentifier may comprise an IP address of the third base station. Thetunnel may comprise a logical IP tunneling between the first basestation and the third base station. The transmitting of the tunnelendpoint identifier may be based on the indication parameter (of the oneor more core network paging messages) indicating that an anchor basestation (e.g. the first base station) has a UE context of the wirelessdevice.

In an example, the first base station may receive, from the second corenetwork entity and in response to the first message, a second messagecomprising the tunnel endpoint identifier of the third base station forforwarding the one or more packets. In an example, the second messagemay comprise a UE context release request complete message (e.g. aresponse message for the UE context release request message) and/or apath switch message.

In an example, the first base station may send, to the third basestation, the one or more packets based on the tunnel endpointidentifier. The third base station may forward the one or more packetsto the wireless device via a radio interface. In an example, the sendingof the one or more packets from the first base station to the third basestation may employ a GTP-U protocol. In an example, the first basestation may send a packet sequence number (e.g. PDCP packet sequencenumber) for a packet reordering at the third base station and/or at thewireless device.

In an example embodiment, the first base station may forward the one ormore packets to a new serving base station (e.g. the third base station)of the wireless device when the RAN paging procedure for transmission ofthe one or more packets is failed. The example embodiment may enhancetransmission reliability of packets (e.g. data packets and/or controlplane packets, NAS messages) for an RRC inactive state wireless deviceand/or an RRC idle state wireless device by enabling forwarding downlinkpackets received by an anchor base station to a new serving basestation.

In an example embodiment, there is a need to implement processes fortransmitting downlink packets to a wireless device in an RRC inactivestate when RAN paging process fails. Example embodiments describe how abase station initiates a core network paging procedure and forwardsdownlink packets to a new base station that receives a response to apaging message of the core network paging procedure from the wirelessdevice when the base station fails to complete an RNA paging procedurefor downlink packets.

In an example, there may be two potential options to transmit one ormore downlink packets to a wireless device in an RRC inactive state:paging in an RNA along with the wireless device (OPTION1), and/ortransmitting after the wireless device is located (OPTION2). OPTION1benefit from lower latency at the cost of more radio resource since datais transmitted in all cells in RNA. From the power consumption point ofview, other wireless devices in RRC inactive state in the same pagingoccasion may have to decode more data to check if it is the target UE.As for OPTION2: The anchor gNB (base station) with connection to the CNshould initiate paging in the whole RAN based area. The one or moredownlink packets may be only transmitted after UE response to save airresources.

In legacy LTE, UE may send paging response via random access procedurecarrying RRC messages (RRC request/RRC resume) to identification andinitiate protocol setup/resume, as FIG. 7 illustrated.

In legacy system, 4 steps RA may be needed to identify the UE identityand RRC messages may be involved as well. For small data transmittingcase, legacy procedure may be not efficient in terms of signallingoverhead and latency. In this case, RRC messages may be used for 3 mainreasons: 1). UE resolution. 2). Configure related parameters/protocols3) state transit to Connected for better scheduling data. Since UE ininactive state has already stored AS contexts and DL data packet size islimited, while UE resolution can be handled by other schemes, directsmall data transmitting without RRC message involvement may be possiblefor inactive state. For example, as illustrated in FIG. 8, suchprocedure may significantly reduce signalling overhead and latency.

In an example, paging may carry the message indicating direct small datatransmission in inactive other than state transition which may makedifference on UE behaviors. A UE receiving the paging may send UE ID onpre-configured contention based resources (e.g. grant free/ preamble+UEID, wherein UE ID used here may be valid at least in RAN notificationarea). The gNB receiving may confirm the UE location upon the receptionof UE ID, and then, if needed, may fetch the UE context and schedule DLdata transmission on a pre-configured receiving window along with ULgrant for ACK. Latency may be further reduced by forwarding UE contextalong with paging message on Xn interface. Acknowledgement may be sentusing UL grant received.

If the UE position is known at cell level, direct DL transmissionwithout paging may be considered. Since the UE may be monitoring paging,one possibility may be to schedule data transmission with unique UE IDdirectly during a UE paging occasion. UE ID may be S-TMSI/long UE IDvalid in RAN notification area or C-RNTI in INACTIVE state. If DL datais scheduled based on common RNTI and long UE ID is indicated in MAC CEthen other INACTVE UEs receiving the data may need to further check longUE ID, it may require more potential power consumption. If there isvalid C_RNTI then C-RNTI may be preferred which may be similar as UMTSCELL_FACH.

Upon data reception, the UE may need to send feedback to RAN side. Thedata transmission may include an indication whether the UE continuesmonitor PDCCH for subsequent data reception or not. If the UE does notmonitor PDCCH subsequently, the network may wait until the next pagingoccasion to send data.

Using UL based mobility, the network may have enough information sothat, instead of paging the UE in one or multiple cell, a dedicatedtransmission to the UE may be possible, even using beam forming, whichgreatly may enhance transmission efficiency.

For a UE with DL based mobility, i.e. cell reselection, the timeinterval since last interaction between the UE and the network may beconsidered. If interactions are frequent, e.g. when DL acknowledgementarrives soon after UL transmission, the network may assume that the UEis still camping on the same cell. DL data may be forwarded directly tothis cell to be transmitted. If ACK is not received, then the networkmay forward the information to its neighbors or start paging.

In an example, when a wireless device is in an RRC inactive state, acore network entity may transmit downlink packets for the wirelessdevice to an anchor base station, which has a wireless device context ofthe wireless device, and the anchor base station may initiate an RNApaging procedure to forward the downlink packets. In an example, thedownlink packets may require an RRC connected state of the wirelessdevice, and/or may be transmitted to the wireless device staying in theRRC inactive state. The RNA paging procedure may comprise transmitting afirst RNA paging message to a plurality of base stations belonging to anRNA associated with the wireless device by the anchor base stationand/or broadcasting a second RNA paging message via a radio interface bybase stations that receives the first RNA paging message. In an example,if the wireless device receives the second RNA paging message, it maytransmit a first RNA paging response to the base station thattransmitted the second RNA paging message. After receiving the first RNApaging response, the base station may transmit a second RNA pagingresponse to the anchor base station.

In an example, the first RNA paging message may comprise at least one ofan RNA identifier, an AS context identifier, a wireless deviceidentifier, and/or a reason of the RNA paging. A base station receivingthe first RNA message may broadcast/multicast the second RNA pagingmessage in one or more beam coverage area and/or in one or more cellcoverage area at least based on the RNA identifier. In an example, thesecond RNA paging message may comprise at least one of an AS contextidentifier, a wireless device identifier, and/or a reason of the RNApaging. The wireless device, which is a target of the RNA paging, mayrecognize the second RNA paging message based on at least one of the AScontext identifier and/or a wireless device identifier, and may performa random access procedure to transmit the first RNA paging response atleast based on the reason of the RNA paging, wherein the random accessprocedure may be one of a 2-stage random access and/or a 4-stage randomaccess. In an example, the first RNA paging response may comprise an RRCconnection request. In an example, the second RNA paging response maycomprise a wireless device context fetch request.

In an example, if an anchor base station does not receive a second RNApaging response after initiating an RNA paging procedure for downlinkpackets, the anchor base station may transmit a core network pagingrequest message to a core network entity. The core network pagingrequest message may be configured to initiate a core network pagingprocedure by the core network entity. The core network paging proceduremay comprise transmitting a first core network paging message to aplurality of base stations belonging to a tracking area associated withthe wireless device by the core network entity and/orbroadcasting/multicasting a second core network paging message via aradio interface by base stations that receives the first core networkpaging message. In an example, if the wireless device receives thesecond core network paging message, it may transmit a first core networkpaging response to the base station that transmitted the first corenetwork paging message. In an example, the first core network pagingresponse may be one of messages of a 2-stage random access and/or a4-stage random access procedure. In an example, the first core networkpaging response may comprise an RRC connection request.

In an example, the first core network paging message may comprise a basestation identifier of the anchor base station. A first base stationreceiving a first core network paging response may determine whetherthere is a direct interface (e.g. Xn interface) between the anchor basestation and the first base station at least based on the base stationidentifier of the anchor base station.

In an example, the first base station in response to receiving the firstcore network paging response may transmit a tunnel endpoint identifierof the first base station to a core network entity, and the core networkentity may forward the tunnel endpoint identifier of the first basestation to the anchor base station. In an example, the anchor basestation may forward one or more downlink packets for the wireless deviceto the first base station at least based on the tunnel endpointidentifier of the first base station. In an example, the first basestation may forward the one or more downlink packets to the wirelessdevice via a radio signaling. In an example, the radio signaling may beone or more messages of a random access procedure, and/or may be apacket transmission through a radio bearer established between the firstbase station and the wireless device in an RRC connected state.

In an example, the first base station may transmit a tunnel endpointidentifier of the first base station to the anchor base station, and theanchor base station may forward one or more downlink packets for thewireless device to the first base station at least based on the tunnelendpoint identifier. In an example, the first base station may forwardthe one or more downlink packets to the wireless device via a radiosignaling. In an example, the radio signaling may be one or moremessages of a random access procedure, and/or may be a packettransmission through a radio bearer established between the first basestation and the wireless device in an RRC connected state.

In an example, the first base station may transmit a first tunnelendpoint identifier of the first base station to the core networkentity, and the core network entity may transmit a second tunnelendpoint identifier of a user plane core network entity to the anchorbase station. In an example, the anchor base station may forward one ormore downlink packets for the wireless device to the user plane corenetwork entity at least based on the second tunnel endpoint identifier,and the user plane core network entity may forward the one or moredownlink packets to the first base station at least based on the firsttunnel endpoint identifier received from the core network entity. In anexample, the first base station may forward the one or more downlinkpackets to the wireless device via a radio signaling. In an example, theradio signaling may be one or more messages of a random accessprocedure, and/or may be a packet transmission through a radio bearerestablished between the first base station and the wireless device in anRRC connected state.

In an example, the tunnel endpoint identifier of the first base stationmay be an IP address of the first base station, and the tunnel endpointidentifier of the user plane core network entity may be an IP address ofthe user plane core network entity.

In an example, the first base station in response to receiving the firstcore network paging response may transmit a wireless device contextrequest message to the anchor base station via an Xn interface, and theanchor base station may transmit a wireless device context to the firstbase station. In an example, the first base station in response toreceiving the first core network paging response may transmit a wirelessdevice context request message to an anchor base station indirectlythrough a core network entity, and the anchor base station may transmita wireless device context to the first base station through the corenetwork entity.

In an example, a base station may receive, from a first network entity,one or more packets for a wireless device in RRC inactive state. Thefirst base station may perform an RNA paging procedure, comprisingtransmitting to one or more second base stations a first message. Thefirst message may comprise an identifier of the wireless device. Thefirst base station may determine that the RNA procedure is unsuccessful.The first base station may transmit, to a second network entity and inresponse to the determining that that the RNA paging procedure isunsuccessful, a second message, wherein the second message initiates acore network paging procedure. The first base station may receive athird message indicating a data forwarding procedure in response to thecore network paging procedure determining that the wireless device maybe in the coverage area of a second base station. The first base stationmay forward the one or more packets to the second base station. In anexample, the first network entity may be the second network entity.

In an example, the forwarding, by the first base station to the secondbase station, may employs a direct tunnel between the first base stationand the second base station, and/or may transmit the one or more packetsto a core network node. The first base station may transmit a PDCPsequence number of one of the one or more downlink data packets. Thesecond message may comprise the PDCP sequence number.

Example of Radio Access Network Area Information

In an example embodiment, an issue with respect to exchanging an RNAinformation between base stations is how a base station gets an RNAinformation of its neighbor cells or its neighbor base stations andemploys the information when the base station initiates a RNA pagingprocedure for a wireless device in an RRC inactive state.

In an existing RAN paging procedure, a base station may configure awireless device with one or more RAN area (e.g. RAN notification area,RAN paging area, one or more cells associated with the RAN area) for anRRC inactive state. The base station may initiate a RAN paging procedurewhen the base station has packets, control signaling, and/or statetransition cause for the wireless device by transmitting a RAN pagingmessage to one or more base stations. The wireless device in the RRCinactive state may receive paging indications from the one or more basestations and/or from the base station based on the one or more RANareas. Implementation of existing signaling when paging an RRC inactivestate wireless device may result in increased network resourceutilization, increased paging delay, increased packet loss rate, and/orincreased call drop rate due to inefficient paging procedure for awireless device in an RRC inactive state. An existing RAN areacoordination may need further enhancements in communication amongnetwork nodes (e.g. base stations, core network entity, wirelessdevice). In an example, failure rate in transmitting a RAN pagingmessage (e.g. for data packets, NAS/RRC signaling packets) may increasefor RRC inactive state wireless devices. Increased RAN paging failurerate may degrade network system reliability. There is a need to improvebackhaul signaling for RRC inactive state wireless devices.

Example embodiments enhance information exchange mechanism among networknodes to improve network communication reliability and/or efficiencywhen a wireless device is in an RRC inactive state. Example embodimentsmay enhance signaling procedures for exchanging RAN area informationamong base stations. In an example embodiment as shown in FIG. 16 andFIG. 17, a base station may transmit its RAN area information (e.g. RANarea identifier, RAN notification identifier, one or more cellinformation of a RAN area). Based on the RAN area information ofneighbor base stations (or neighbor cells), a base station may enhance aRAN paging reliability for an RRC inactive state wireless device bysending a RAN paging message to neighboring base station associated witha RAN area of the RRC inactive state wireless device. Exampleembodiments may increase backhaul signaling efficiency by limiting a RANpaging message transmission to a corresponding base stations that isassociated with a RAN area of a RAN paging target wireless device.

In an example, a base station may perform an Xn setup procedure to setupan Xn interface with its neighbor base station. The Xn setup proceduremay comprise a first message received by a first base station from asecond base station and/or a second message transmitted by the firstbase station to the second base station in response to the firstmessage. In an example, the first message may be an Xn setup requestmessage, and the second message may be an Xn setup response message. Thefirst message may comprise at least one of a gNB identifier of thesecond base station, a cell identifier of a cell served by the secondbase station, and/or an RNA identifier, wherein the RNA identifier maybe associated with the second base station and/or a cell of the secondbase station. The second message may comprise at least one of a gNBidentifier of the first base station, a cell identifier of a cell servedby the first base station, and/or an RNA identifier associated with thefirst base station and/or a cell of the first base station.

In an example, a base station may perform a gNB configuration updateprocedure to update configuration information of its neighbor basestation. In an example, at least if a cell is added, modified, and/orremoved in a base station, and/or if an RNA information for a basestation or for a cell of a base station is changed, the base station mayinitiate a gNB configuration update procedure. The gNB configurationupdate procedure may comprise a first message received by a first basestation from a second base station and/or a second message transmittedby the first base station to the second base station in response to thefirst message. In an example, the first message may be a gNBconfiguration update message, and the second message may be a gNBconfiguration update acknowledge message. The first message may compriseat least one of a gNB identifier of the second base station, a cellidentifier of a cell served by the second base station, and/or an RNAidentifier, wherein the RNA identifier may be associated with the secondbase station and/or a cell of the second base station. The secondmessage may comprise an acknowledgement of the first message.

In an example, the RNA identifier may comprise RAN notification areainformation, RAN area information (e.g. RAN area identifier), one ormore cell identifiers of one or more cells associated with a RANnotification area (e.g. RAN area, RAN paging area).

In an example embodiment, an RNA identifier may be identifiable globallyand/or in a PLMN. In an example, an RNA identifier exchanged through anXn setup procedure and/or a gNB configuration update procedure may beemployed by a base station to determine a paging area for an RNA pagingprocedure, which may be used to inform a wireless device in an RRCinactive state that at least one of following events occurred: that thebase station received one or more packets for the wireless device; thatthe wireless device is required to transition its RRC state from the RRCinactive state to an RRC idle state; and/or that that the wirelessdevice is required to transition its RRC state from the RRC inactivestate to an RRC connected state. In an example the one or more packetsmay comprise data packets from a user plane core network entity (e.g.UPF) and/or control signaling (e.g. NAS message) from a control planecore network entity (e.g. AMF).

In an example, a base station may transmit, to a wireless device, a RANnotification area information (e.g. RAN area identifier of a RAN area,RAN paging area identifier of a RAN paging area, and/or one or more cellidentifier of one or more cells of the RAN notification area, of the RANpaging area, and/or of the RAN area). The base station may indicate, tothe wireless device, a state transition from an RRC connected state toan RRC inactive state by transmitting an RRC message (e.g. an RRCconnection release message, an RRC connection suspend message). In anexample, the RRC message may comprise the RAN notification areainformation for the wireless device. When the wireless device stays inthe RRC inactive state, the wireless device may move around one or morecells of the RAN notification area. When the wireless device stays inthe RRC inactive state, the wireless device may move out of the RANnotification area, and may initiate a RAN notification area updateprocedure informing, to the base station, that the wireless device movedto a different RAN notification area from the RAN notification area. TheRAN notification area may comprise a RAN area of the neighboring basestation, information of the RAN area received from the neighboring basestation via the Xn setup request/response message and/or the gNBconfiguration update message.

In an example, the RNA paging procedure may comprise transmitting afirst RNA paging message by a first base station to a plurality ofsecond base stations belonging to an RNA associated with the wirelessdevice and/or broadcasting/multicasting a second RNA paging message viaa radio interface by a plurality of the second base stations thatreceives the first RNA paging message, wherein the first base stationmay be an anchor base station of the wireless device. In an example, ifthe wireless device receives the second RNA paging message, it maytransmit a first RNA paging response to the base station that itreceived the second RNA paging message from. After receiving the firstRNA paging response, the base station may transmit a second RNA pagingresponse to the first base station, an anchor base station of thewireless device. In an example, the second RNA paging response maycomprise a wireless device context request.

In an example embodiment, during an RNA paging procedure, a first RNApaging message transmitted from a first base station to a plurality ofsecond base stations may comprise at least one of an identifier of awireless device, an AS context identifier for a wireless device, an RNAidentifier, and/or a reason of the RNA paging for the wireless device tonotify a plurality of second base station of at least one of downlinkpackets for the wireless device, an RRC state transition required froman RRC inactive state to an RRC idle state, and/or an RRC statetransition required from an RRC inactive station to an RRC connectedstate. In an example, a first RNA paging message may be transmitted toone or more base stations that serve at least one cell belonging to anRNA associated with a wireless device, a target device of an RNA pagingprocedure. The first base station may determine the one or more basestations (e.g. RAN paging target base station) based on the RNAinformation received from the one or more base stations. In an example,when the RNA information comprises a cell and/or a RAN area that wasconfigured to the wireless device (e.g. when transitioning an RRC stateto the RRC inactive state), the first base station transmit an RANpaging message to a base station that transmitted the RNA information.

In an example embodiment, during an RNA paging procedure, a second RNApaging message broadcasted/multicasted by a second base station maycomprise at least one of an AS context identifier for a wireless device,an identifier of a wireless device, and/or a reason of the RNA paging tonotify the wireless device of at least one event of downlink packets forthe wireless device, an RRC state transition required from an RRCinactive state to an RRC idle state, and/or an RRC state transitionrequired from an RRC inactive station to an RRC connected state. In anexample, a second RNA paging message may be broadcasted and/ormulticasted in a coverage area of the second base station, in a coveragearea of a cell belonging to an RNA, and/or a coverage area of a beam ofa cell belonging to an RNA.

In an example embodiment, after an RNA paging procedure, if an anchorbase station receives a second RNA paging response from a base stationthat received a first RNA paging response from a wireless device in anRRC inactive state, which is a target device of the RNA pagingprocedure, the anchor base station may forward one or more packets tothe base station that transmitted the second RNA paging response in casethat the reason of the RNA paging is to transmit the one or more packetsfor the wireless device. In an example, the second RNA paging responsemay comprise a UE context retrieve request message for the wirelessdevice. In an example, the second RNA paging response message maycomprise a resume identifier for the wireless device, and the anchorbase station may retrieve a UE context based on the resume identifier.In an example, the first RNA paging response may comprise a RRC contextresume/setup request message. The first RNA paging response may comprisethe resume identifier of the wireless device for the RRC inactive state.The base station receiving the first RNA paging response may identifythe anchor base station based on the resume identifier, and may transmitthe second RNA paging response message.

In an example, the anchor base station receiving the second RNA pagingresponse may release a UE context of the wireless device in case thatthe reason of the RNA paging procedure is to initiate an RRC statetransition of the wireless device. If the RRC state transition istransitioning to an RRC connected state, the anchor base station maytransmit one or more elements of the UE context of the wireless deviceto the base station that transmitted the second RNA paging responsebefore release the UE context. If the RRC state transition istransitioning to an RRC idle state, the anchor base station may releasethe UE context without transmitting at least one element of the UEcontext to a base station.

In an example, a first base station may receive, from a second basestation, a first message comprising a first radio access networknotification area (RNA) identifier associated with the second basestation. The first base station may transmit to the second base stationa second message comprising an identifier of a wireless device when thefirst base station is also associated with the first RNA identifier.

In an example, a first base station may receive, from a second basestation, a first message comprising a first radio access networknotification area (RNA) identifier associated with the second basestation. The first base station may transmit to a wireless device, oneor more third messages comprising radio configuration parameters,wherein the radio configuration parameters may comprise the RNAidentifier, and the wireless device may be in a radio resource control(RRC) connected state. The first base station may initiate a procedureto transition the wireless device from the RRC connected state to an RRCinactive state. The first base station may transmit to the second basestation a second message comprising an identifier of the wireless devicewhen the first base station is also associated with the first RNAidentifier, wherein the wireless device may be in a radio resourcecontrol (RRC) inactive state and configured with the first RNAidentifier. The second message may be configured to initiatebroadcasting and/or multicasting, by the second base station, a thirdmessage comprising an indication. The second message may be configuredto initiate broadcasting or multicasting, by the second base station andin a coverage area or a beam area of the second base station, a thirdmessage comprising an indication.

In an example, the second message may be a paging message. Theindication may be a paging indication. The first base station mayfurther transmit to one or more third base stations one or more thirdmessages comprising the identifier of the wireless device. Theindication may be configured to cause the wireless device to change froman RRC inactive state to an RRC idle state. The indication may beconfigured to cause the wireless device to change from an RRC inactivestate to an RRC connected state. The indication may indicate one or moredownlink data packets for the wireless device. The wireless deviceand/or at least one base station may release a wireless device context.The second base station may receive a fourth message comprising an RRCconnection request from the wireless device. The second base station maytransmit, to the first base station, a fifth message comprising arequest of a wireless device context for the wireless device. The secondbase station may receive a sixth message comprising the wireless devicecontext from the first base station.

In an example, at least one base station may have a wireless devicecontext of the wireless device in an RRC inactive station, and thewireless device may have no RRC connection with the at least one basestation having the wireless device context. A wireless device contextmay comprise at least one of a bearer configuration information, alogical channel information, a security information, a PDCPconfiguration information, AS context, and one or more parameters forthe wireless device. The RNA identifier may be associated with a cell ofthe second base station. The first base station may be also associatedwith the first RNA identifier when at least one cell in the first basestation is associated with the first RNA identifier. The first basestation may be associated with a plurality of RNA identifier. The firstbase station may transmit a message comprising the first RNA identifierto the second base station. The first base station may transmit thesecond message in response to receiving at least one data or controlpacket from a core network entity. The first base station may receive amessage from a network entity comprising the first RNA identifier.

Example of Radio Access Network Paging Area Configuration

In an example embodiment, an issue with respect to determining an areafor an RNA paging is how a base station transmits a paging message to awireless device in an RRC inactive state by broadcasting a pagingmessage in a limited area for signaling efficiency.

In an existing RAN paging procedure, base stations exchanges backhaulsignaling to transmit a downlink packets to a wireless device in an RRCinactive state. A base station may transmit paging messages via itscells and/or to its neighboring base stations of a RAN notification areaassociated with the wireless device. Implementation of existing backhaulsignaling may result in increased network resource utilization due toinefficient RAN paging message transmission. An inefficient RAN pagingprocedure may need further enhancement in communication and/orcontrolling mechanism of network nodes (e.g. base stations, core networkentity, and wireless device). In an example, increased signaling loadfor RAN paging procedure to wake up an RRC inactive state wirelessdevice may increase backhaul signaling delay and may decrease signalingreliability. Increased packet loss rate caused due to signaling overheadmay degrade network system reliability. There is a need to improvebackhaul signaling mechanism of a RAN paging procedure for RRC inactivestate wireless devices. Example embodiments enhance RAN paging mechanismby enabling a base station to employ a time duration since a signalingwith a RAN paging target wireless device in an RRC inactive state, inselecting a RAN paging target base station. In an example, bytransmitting a RAN paging message to a neighbor base station thatcommunicated with the wireless device recent, a base station may avoidunnecessary signaling for RAN paging messages to other base stations,which are unlikely to be selected by the RAN paging target wirelessdevice.

In an example embodiment as shown in FIG. 18 and FIG. 19, a base station(e.g. an anchor base station, gNB) may determine a time duration betweenreceiving/transmitting recent packets from/to a wireless device andreceiving packets from a core network entity (e.g. AMF) for the wirelessdevice. In an example, the packets form the core network entity maycause the base station initiates a RAN paging procedure. Based on thetime duration, the base station may select a target base station towhich the base station transmits a RAN paging message for the wirelessdevice. In an example, when the time duration is smaller than and/orequal to a first time value, the base station may transmit a RAN pagingmessage to a second base station that sent/received the recent packetsto/from the base station. In an example, when the time duration islarger than the first time value, the base station may transmit RANpaging messages to third base stations belonging to a RAN notificationarea associated with the wireless device. In an example, the third basestations may comprise the second base station.

In an example, as shown in FIG. 20 and FIG. 21, if the base stationreceives/transmit recent packets from the wireless device via its cell,the base station may transmit RAN paging messages (e.g. radio interfacepaging) via its cell when the time duration is smaller than and/or equalto a first time value, and the base station may transmit RAN pagingmessages to second base stations belonging to a RAN notification areaassociated with the wireless device when the time duration is largerthan the first time value.

In an example embodiment, by limiting a RAN paging area based on a timeduration since a recent communication with a wireless device, a basestation may reduce signaling overhead for unnecessary RAN paging messagetransmissions.

In an example embodiment, a first base station may determine a pagingarea for an RNA paging procedure and/or a core network paging proceduretargeting a wireless device in an RRC inactive state at least based on atime duration between a latest signaling with the wireless device and anoccurrence of an event requiring a paging message transmission, and thefirst base station may transmit a paging message in the determinedpaging area. A first paging timer may be configured in the base station.The base station may restart the first paging timer in response toreceiving and/or transmitting a paging message and/or a pre-definedsignaling between the first base station and wireless device (e.g.uplink data transmission, random access preamble, downlink datatransmission, ACK, etc.). For example, the base station may consider aprevious location of the wireless device if the paging process isstarted when the first paging timer is running The base station may pagethe wireless device in the RNA area or core TA area when the pagingprocess starts after the timer is expired.

In an example, a first base station may determine a paging area based onat least one of a moving speed of a paging target wireless device, aservice type (e.g. a logical channel type, a bearer type, a slice type,and etc.) of a paging target wireless device, a subscription informationof a paging target wireless device, a establish cause of a paging targetwireless device, a mobility information of a paging target wirelessdevice, and/or a mobility estimation information of a paging targetwireless device.

In an example, the determined paging area may be at least one of one ormore base stations in an RNA, one or more cells of a base station in anRNA, and/or one or more beams of a cell operated by a base station in anRNA. In an example, if the determined paging area completely orpartially belongs to coverage areas of one or more second base stations,the first base station that determined the paging area may transmit afirst paging message to the one or more second base stations, and theone or more second base stations may broadcast and/or multicast a secondpaging message in their coverage area. In an example, if the determinedpaging area completely or partially belongs to a coverage area of thefirst base station that determined the paging area, the first basestation may broadcast and/or multicast a second paging message in itscoverage area. In an example, if the determined paging area only belongsto a coverage area of the first base station, the first base station maynot transmit a first paging message.

In an example, if the determined paging area belongs to a coverage areaof a first cell of the first base station, the first base station maybroadcast and/or multicast a second paging message in the first cell. Inan example, if the determined paging area belongs to a coverage area ofa first beam in a first cell of the first base station, the first basestation may broadcast and/or multicast a second paging message in thefirst beam.

In an example, the first paging message transmitted from the first basestation to the one or more second base stations may comprise at leastone of a wireless device identifier of a wireless device targeted for apaging and/or an RNA identifier, and the second paging messagebroadcasted and/or multicasted by the first base station and/or the oneor more second base stations may comprise the wireless deviceidentifier. In an example, a base station receiving the first pagingmessage with an RNA identifier may broadcast and/or multicast the secondpaging message in a coverage area of a cell associated with an RNAidentified by the RNA identifier.

In an example, the latest signaling with the wireless device may be asignaling message transmitted for at least following procedures: arandom access procedure for uplink and/or downlink packet transmissionfor the wireless device (e.g. data and/or control packets), a uplinkand/or downlink packet transmission and/or acknowledge signaling, an RNAupdate and/or tracking area update procedure initiated by the wirelessdevice, an RRC state transition from an RRC connected state to the RRCinactive state, and/or a paging and/or response procedure.

In an example, the event requiring a paging message transmission may beone of at least following events: a downlink packet reception for thewireless device (e.g. data and/or control packets), an event requiringan RRC state transition of the wireless device to an RRC connected state(e.g. receiving one or more downlink packets for a service requiring anRRC connected state, receiving a command from a core network entity thatrequests an RRC connected state of the wireless device, a timerexpiration for an RRC inactive state, a high load of random accessprocedure attempts, and/or other abnormal events), and/or an eventrequiring an RRC state transition of the wireless device to an RRC idlestate (e.g. receiving a command from a core network entity that requestsan RRC idle state of the wireless device, a timer expiration for an RRCinactive state, a high load of random access procedure attempts, and/orother abnormal events).

In an example, the random access procedure for uplink and/or downlinkpacket transmission may be initiated by a wireless device in an RRCinactive state at least when its buffer has one or more packets totransmit and/or when the wireless device receives a paging message forone or more downlink packets from a base station. In an example, therandom access procedure may be performed with two messages (e.g. 2-stagerandom access) and/or four messages (e.g. 4-stage random access).

In a 2-stage random access procedure, a first message may be transmittedby a wireless device to a base station, and the first message maycomprise at least one of a random access preamble and/or one or moreuplink packets. A second message of the 2-stage random access proceduremay be transmitted to the wireless device by the base station receivingthe first message, and the second message may comprise anacknowledgement of a reception of the one or more uplink packets. In anexample, the second message of the 2-stage random access procedure mayfurther comprise a resource grant for further uplink packettransmission, and the wireless device may transmit a third messagecomprising one or more packets at least based on the resource grant. Thebase station receiving the third message may transmit an acknowledgementand/or further resource grant for further uplink packet transmission. Inan example, further resource grants by the base station and associatinguplink packet transmissions by the wireless device may be continuedthrough further messages.

In a 4-stage random access procedure, a first message may be transmittedby a wireless device to a base station, and the first message maycomprise at least one of a random access preamble and/or one or moreuplink packets. A second message of the 4-stage random access proceduremay be transmitted to the wireless device by the base station receivingthe first message, and the second message may comprise a resource grantfor uplink packet transmission. A third message of the 4-stage randomaccess procedure may be transmitted by the wireless device to the basestation at least based on the resource grant in the second message, andmay comprise one or more uplink packets. A fourth message transmitted bythe base station to the wireless device may comprise an acknowledgementof a reception of the one or more uplink packets. In an example, thefourth message of the 4-stage random access procedure may furthercomprise a further resource grant for further uplink packettransmission, and the wireless device may transmit a fifth messagecomprising one or more packets at least based the further resource grantin the fourth message. The base station receiving the fifth message maytransmit an acknowledgement and/or further resource grant for furtheruplink packet transmission. In an example, further resource grants bythe base station and associating uplink packet transmissions by thewireless device may be continued through further messages.

In an example, the RNA update procedure may be initiated by a wirelessdevice in an RRC inactive state at least when the wireless deviceselects a cell belonging to a new RNA and/or when a time threshold for aperiodic RNA update is expired. In an example, a base station mayconfigure a wireless device to perform an RNA update periodically whenthe time threshold is expired. In an example, a cell may broadcast oneor more RNA identifier for one or more RNA associated with the cell, anda wireless device may determine whether one of the broadcasted one ormore RNA identifier is same to its RNA identifier assigned in at leastone of a cell in which the wireless device performed the latest RNAupdate procedure, a cell in which the wireless device performed thelatest uplink and/or downlink packet transmission, and/or a cell inwhich the wireless device was in an RRC connected state most recently.

In an example, the RNA update procedure may comprise at least one of arandom access procedure initiated by a wireless device in an RRCinactive state, a wireless device context fetch procedure initiated by anew base station, a path switch procedure initiated by a new basestation, and/or storing a RNA identifier of a new RNA by a wirelessdevice. In an example, the wireless device context fetch procedure maycomprise requesting, by the new base station to an old anchor basestation of a wireless device, a wireless device context for the wirelessdevice initiating the RNA update procedure, and/or receiving, by the newbase station from the old anchor base station, the wireless devicecontext. In an example, the wireless device context may comprise atleast one of an AS context, a bearer configuration information, asecurity information, a PDCP configuration information, and/or otherconfiguration information for the wireless device. In an example, thepath switch procedure may comprise requesting, by the new base stationto a core network entity, to update a downlink tunnel endpointidentifier for one or more bearers established for the wireless devicebetween a user plane core network entity and a RAN node (e g changing adownlink tunnel endpoint identifier from an address of the old anchorbase station to an address of the new base station).

In an example, the tracking area update procedure may be initiated by awireless device in an RRC inactive state (and/or in an RRC idle state)at least when the wireless device selects a cell belonging to a newtracking area and/or when a time threshold for a periodic tracking areaupdate is expired. In an example, a core network entity may configure awireless device to perform a tracking area update periodically when thetime threshold is expired. In an example, a cell may broadcast one ormore tracking area identifier for one or more tracking area associatedwith the cell, and a wireless device may determine whether one of thebroadcasted one or more tracking area identifier is same to its trackingarea identifier assigned in at least one of a cell in which the wirelessdevice performed the latest tracking area update procedure, (a cell inwhich the wireless device performed the latest uplink and/or downlinkpacket transmission,) and/or a cell in which the wireless device was inan RRC connected state most recently.

In an example, the RRC state transition from an RRC connected state tothe RRC inactive state may be completed by a first RRC messagetransmitted by a base station to a wireless device in an RRC connectedstate. The first RRC message may comprise a command for the RRC statetransition of the wireless device. In an example, the wireless devicemay transmit an acknowledgement via a second RRC message, a MAC layermessage, and/or a physical layer message.

In an example, the paging and response procedure may comprise a pagingmessage broadcasted/multicasted by a base station for an RNA pagingand/or a core network paging, and/or a random access procedure. Therandom access procedure may be a 2-stage random access procedure and/ora 4-stage random access procedure.

In an example, the downlink packet reception for the wireless device maybe a reception of one or more packets for the wireless device from acore network entity and/or an anchor base station. The downlink packetreception for the wireless device may require an RNA paging procedure.In an example, a base station that received the one or more packets maymeasure a time duration from a latest signaling with the wireless deviceand an occurrence of the downlink packet reception, and may determine apaging area for an RNA paging.

In an example, the event requiring an RRC state transition of thewireless device to an RRC connected state in a base station may be atleast one of receiving one or more downlink packets for the wirelessdevice, receiving an RRC state transition request for the wirelessdevice from a core network entity, and/or a decision by the base stationof the RRC state transition. In an example, the base station may measurea time duration from a latest signaling with the wireless device and anoccurrence of the event requiring an RRC state transition, and maydetermine a paging area for an RNA paging and/or a core network paging.

In an example, the event requiring an RRC state transition of thewireless device to an RRC idle state in a base station may be one ofreceiving an RRC state transition request for the wireless device from acore network entity and/or a decision by the base station of the RRCstate transition. In an example, the base station may measure a timeduration from a latest signaling with the wireless device and anoccurrence of the event requiring an RRC state transition, and maydetermine a paging area for an RNA paging and/or a core network paging.

In an example, a first base station may receive or transmit a firstmessage associated with a wireless device in an RRC inactive state. Thefirst base station may determine which selected base station is selectedby the wireless device. The first base station may receive, from a corenetwork node, a downlink data packet for the wireless device. The firstbase station may determine whether a time duration between a receptionof the first messages and a reception of the downlink data packet issmaller than a first time period. When the first base station is thesame as the selected base station and when the determination indicatesthe time duration is smaller than the first time period, the first basestation may transmit one or more second messages comprising at least oneof a downlink data indication and at least one of the one or moredownlink data packets.

In an example, when the first base station is the same as the selectedbase station and when the determination indicates the time duration isnot smaller that the first time period, the first base station maytransmit, to a plurality of base stations, one or more third messagescomprising an indication of a downlink data. When the first base stationis different from the selected base station and when the determinationindicates the time duration is smaller than the first time period, thefirst base station may transmit, to a second base station, one or moresecond messages comprising at least one of a downlink data indicationand at least one of the one or more downlink data packets. When thefirst base station is different from the selected base station and whenthe determination indicates the time duration is not smaller that thefirst time period, the first base station may transmit, to a pluralityof base stations, one or more third messages comprising an indication ofa downlink data.

In an example, the first message may be at least one uplink signalingtransmission of: an uplink data transmission procedure in the RRCinactive state, a downlink data transmission procedure in the RRCinactive state, an RNA update procedure, and/or a procedure of an RRCstate transition from an RRC connected state to the RRC inactive state.The first time period may be defined at least based on a moving speed ofthe wireless device. The limited area may be determined at least basedon one of: a moving speed of the wireless device, a size of the cellwhere the one or more first messages were transmitted, and/or a size ofthe beam area where the one or more first messages were transmitted. Atleast one base station may have a UE context of the wireless device inthe RRC inactive state, and the wireless device in the RRC inactivestate may not have an RRC connection with the at least one base stationhaving the UE context.

Example of Cell Selection of Inactive State Wireless Device

In an example embodiment, an issue with respect to selecting a cell by awireless device in an RRC inactive state or an RRC idle state is how awireless device determines a cell that supports a service that thewireless device may likely receive, the determination to reduce furthersignaling to assign a cell providing the service.

In an existing network mechanism, a wireless device being in an RRCinactive state may select/reselect cell to camp on based on a receivedpower and/or quality from one or more cells. The wireless device mayemploy a certain type of services (e.g. network slice, bearer, logicalchannel, QoS flow, PDU session). In an example, a cell may not support aspecific type of services. For example, a cell may support differenttypes of numerologies, TTIs, subcarrier spacing configurations, and/orlicensed/unlicensed spectrums. The different types of numerologies,TTIs, subcarrier spacing configurations, and/or licensed/unlicensedspectrums may be employed for a specific type of services. In anexample, a small TTI configuration may support a URLLC type service(network slice) for a low latency requirement, and/or an unlicensedspectrum may not support the URLLC type service due to its lessreliability. In an example, some limited cells may support a configuredgrant type 1 (e.g. grant-free uplink resources), which may be requiredfor a URLLC services and/or an IoT (e.g. MTC) service.

In an example, if a wireless device select/reselect a cell that does notsupport a service type required by the wireless device, the wirelessdevice may require increased signaling with a base station to reselect acell supporting the service type and/or to perform a handover or asecondary cell addition procedure to employ a cell supporting theservice type. The increased signaling caused by selecting a cell thatdoes not support a required service type may increase communicationdelay, packet loss, and/or communication reliability. Example embodimentenhance a cell selection/reselection procedure by enabling a basestation to configure associations between a cell (e.g. cell type,registration area, numerology, TTI, subcarrier spacing, spectrum band)and a service type (e.g. network slice, bearer, logical channel, QoSflow, PDU session) for a wireless device in an RRC inactive state(and/or an RRC idle state).

In an example, in an RRC idle state, a wireless device may not have alogical channel (and/or a bearer) activated, and the wireless device mayneed a RRC connection to transmit/receive data for a service. Unlike theRRC idle state, in an RRC inactive state, a wireless device may beconfigured with one or more logical channels (and/or one or morebearers), and the wireless device may have a configured buffer to queuepackets associated with the one or more logical channels in the RRCinactive state (without transitioning to an RRC connected state).

In an example embodiment, as shown in FIG. 22, FIG. 23, and FIG. 24, acell may or may not support a service to a wireless device. The servicemay be associated with at least one of a logical channel, a bearer, aslice, a UE type, and/or a categorized type for packet transmission. Inan example, a base station may configure a wireless device to employ oneor more cells and/or cell types to transmit a packet for a logicalchannel The configuration may be provided to the wireless device via oneor more dedicated RRC messages and/or one or morebroadcasted/multicasted system information messages. In an example, abase station may broadcast/multicast a cell identifier and/or a celltype information via a system information message of a cell. In anexample, a cell of a base station may broadcast/multicast a restrictedand/or allowed service list (e.g. a logical channel type list, a bearertype list, and/or a slice list). In an example, the wireless device inan RRC inactive state and/or an RRC idle state may select a cell, atleast based on the broadcasted/muticasted information by a cell, for atleast one of purposes: to receive a paging message for an RNA pagingand/or a core network paging (e.g. a tracking area paging) for receptionof one or more downlink packets and/or an RRC state transition command,to transmit one or more uplink packets, and/or to initiate an RRC statetransition to an RRC connected state. In an example, when the wirelessdevice in an RRC inactive state gets data for a first logical channel(e.g. first bearer) in corresponding buffer, the wireless device mayselect/reselect a cell configured, by a base station, for the firstlogical channel (or the first bearer), and may transmit the data to thebase station via the cell. In an example, when the wireless device in anRRC inactive state gets data for a first service type (e.g. firstnetwork slice) in corresponding buffer, the wireless device mayselect/reselect a cell configured, by a base station, for the firstservice type (or the first network slice), and may transmit the data tothe base station via the cell. The cell may be configured as aregistration area, a cell type (e.g. numerology, TTI, subcarrierspacing, spectrum band), and/or the like.

In an example, a wireless device may receive/transmit, from/to a basestation, one or more packets via one or more logical channels and/or oneor more bearers for one or more services. When a base stationestablishes a radio bearer and/or a logical channel for a wirelessdevice, the base station may provide, to the wireless device, a list ofcells and/or cell types that may be employed to transmit one or morepackets associated with a logical channel and/or a bearer. In anexample, if the wireless device is in an RRC connected state, the listof cells and/or cell types for a logical channel and/or a bearer may betransmitted via one or more RRC message. In an example, the list ofcells and/or cell types for a logical channel and/or a bearer may betransmitted via one or more MAC CEs. In an example, a cell maybroadcast/multicast a list of one or more restricted and/or allowedlogical channel types, bearer types, and or slice types, wherein thelist may be transmitted via one or more system information messages.

In an example, a wireless device in an RRC inactive state may select acell to further receive an RNA paging message or a core network pagingmessage. The RNA paging message or the core network paging message maybe transmitted by a base station to transmit one or more downlinkpackets to the wireless device, the one or more downlink packetsassociated with a logical channel and/or a bearer. If the wirelessdevice selects a cell that does not support the logical channel and/orthe bearer, a base station may assign another cell to the wirelessdevice to transmit the one or more downlink packets after the wirelessdevice response to the paging message. In an example, if the wirelessdevice selects a cell that may support the logical channel and/or thebearer, the base station may not need to assign another cell to transmitthe one or more downlink packets.

In an example, if a first logical channel and/or bearer is establishedfor a wireless device and if one or more cells and/or cell types areconfigured by a base station for the first logical channel and/orbearer, the wireless device in an RRC inactive state may select one ofthe one or more cells and/or cell types for further downlink packetreception associated with the first logical channel and/or bearer atleast based on a broadcasted/multicasted cell identifier and/or celltype in a cell. In an example, the wireless device may not select a cellwhere the first logical channel and/or bearer is associated with a listof one or more restricted logical channel types, bearer types, and orslice types at least based on broadcasted/multicasted information from acell. In an example, the wireless device may select a cell where thefirst logical channel and/or bearer is associated with a list of one ormore allowed logical channel types, bearer types, and or slice types atleast based on broadcasted/multicasted information from a cell.

In an example, a wireless device in an RRC idle state may select a cellto further receive a core network paging message. The core networkpaging message may be transmitted by a base station to transmit one ormore downlink packets to the wireless device, the one or more downlinkpackets associated with a logical channel type and/or a bearer type. Inan example, if a wireless device in an RRC idle state selects a cellthat may support the logical channel and/or the bearer for a servicethat the wireless device may receive, a base station may not need toassign another cell to transmit the one or more downlink packets afterthe wireless device response to a core network paging message.

In an example, if one or more cells and/or cell types are configured bya base station for a first logical channel type and/or bearer type, thewireless device after transitioning to an RRC idle state may select oneof the one or more cells and/or cell types for further downlink packetreception associated with the first logical channel type and/or bearertype at least based on a broadcasted/multicasted cell identifier and/orcell type in a cell. In an example, the wireless device may not select acell where the first logical channel type and/or bearer type isassociated with a list of one or more restricted logical channel types,bearer types, and or slice types at least based onbroadcasted/multicasted information from a cell. In an example, thewireless device may select a cell where the first logical channel typeand/or bearer type is associated with a list of one or more allowedlogical channel types, bearer types, and or slice types at least basedon broadcasted/multicasted information from a cell.

In an example, a wireless device in an RRC inactive state may select acell to further transmit one or more uplink packets to a network. In anexample, a wireless device may transmit one or more uplink packets to abase station via one or more random access procedure in a selected cell,the one or more uplink packets associated with a logical channel and/ora bearer. If the wireless device selects a cell that does not supportthe logical channel and/or the bearer, a base station may assign anothercell to the wireless device to receive the one or more uplink packets.In an example, if the wireless device selects a cell that may supportthe logical channel and/or the bearer, the base station may not need toassign another cell to receive the one or more uplink packets.

In an example, if a first logical channel and/or bearer is establishedfor a wireless device and if one or more cells and/or cell types areconfigured by a base station for the first logical channel and/orbearer, the wireless device in an RRC inactive state may select one ofthe one or more cells and/or cell types for further uplink packettransmission associated with the first logical channel and/or bearer atleast based on a broadcasted/multicasted cell identifier and/or celltype in a cell. In an example, the wireless device may not select a cellwhere the first logical channel and/or bearer is associated with a listof one or more restricted logical channel types, bearer types, and orslice types at least based on broadcasted/multicasted information from acell. In an example, the wireless device may select a cell where thefirst logical channel and/or bearer is associated with a list of one ormore allowed logical channel types, bearer types, and or slice types atleast based on broadcasted/multicasted information from a cell.

In an example, a wireless device in an RRC inactive state and/or an RRCidle state may select a cell to initiate an RRC state transition to anRRC connected state. The wireless device may perform a random accessprocedure to make an RRC connection in the selected cell. Aftercompleting the RRC state transition, the wireless device may transmitand/or receive one or more packets associated with a logical channeland/or a bearer. In an example, if the wireless device selects a cellthat does not support the logical channel and/or the bearer, a basestation may assign another cell to the wireless device to transmitand/or receive the one or more packets after completing the RRC statetransition. In an example, if the wireless device selects a cell thatmay support the logical channel and/or the bearer, the base station maynot need to assign another cell to transmit and/or receive the one ormore packets.

In an example, if a first logical channel and/or bearer is establishedfor a wireless device and if one or more cells and/or cell types areconfigured by a base station for the first logical channel and/orbearer, the wireless device in an RRC inactive state may select one ofthe one or more cells and/or cell types for further packet transmissionand/or reception associated with the first logical channel and/orbearer, after completing an RRC state transition to an RRC connectedstate, at least based on a broadcasted/multicasted cell identifierand/or cell type in a cell. In an example, the wireless device may notselect a cell where the first logical channel and/or bearer isassociated with a list of one or more restricted logical channel types,bearer types, and or slice types at least based onbroadcasted/multicasted information from a cell. In an example, thewireless device may select a cell where the first logical channel and/orbearer is associated with of a list of one or more allowed logicalchannel types, bearer types, and or slice types at least based onbroadcasted/multicasted information from a cell.

In an example, if one or more cells and/or cell types are configured bya base station for a first logical channel type and/or bearer type, thewireless device after transitioning to an RRC idle state may select oneof the one or more cells and/or cell types for further packettransmission and/or reception associated with the first logical channeltype and/or bearer type at least based on a broadcasted/multicasted cellidentifier and/or cell type in a cell. In an example, the wirelessdevice may not select a cell where the first logical channel type and/orbearer type is associated with a list of one or more restricted logicalchannel types, bearer types, and or slice types at least based onbroadcasted/multicasted information from a cell. In an example, thewireless device may select a cell where the first logical channel typeand/or bearer type is associated with a list of one or more allowedlogical channel types, bearer types, and or slice types at least basedon broadcasted/multicasted information from a cell.

In an example, a wireless device may receive, from a base station, afirst messages comprising configuration parameters, wherein theconfiguration parameters may indicate association of a bearer or logicalchannel with one or more cells for the wireless device in a RRCconnected state. The wireless device may receive, from a base station, asecond message comprising an RRC state transition command configured tocause an RRC state transition of the wireless device from the RRCconnected state to an RRC inactive state. The wireless device in the RRCinactive state may select a first cell at least based on one or morecriteria, wherein the one or more criteria may employ at least theconfiguration parameters. The wireless device may transmit to the basestation a random access preamble message via the first cell. Thewireless device in the RRC connected state may have an RRC connectionwith at least one base station. When the wireless device is in the RRCinactive state, at least one base station may have a wireless devicecontext of the wireless device, and/or the wireless device may not havean RRC connection with the at least one base station having the wirelessdevice context. The wireless device context may comprise at least one ofa bearer configuration information, a logical channel information, asecurity information, an AS context, a PDCP configuration information,and other information for the wireless device. The transmitting therandom access preamble message may be in response to at least one of thefollowing: an uplink buffer including one or more data packets, thewireless device receiving a paging indication, and/or the wirelessdevice detecting moving to a new RNA or TA. The association of thebearer or logical channel with one or more cells may compriseassociation of the bearer or logical channel with a cell type and/orcells in a frequency band.

Example of Radio Access Network Notification Area Update Failure

Example embodiments provide methods and system for determining aperiodic RNA update failure in a base station and a wireless device.Example embodiment provides mechanisms for a base station to transmit anotification of the failure to a core network entity. Example embodimentprovides processes in a wireless device when a periodic RNA updateprocess fails.

In an existing RAN notification area update (RNAU) procedure, basestation(s) and/or a wireless device may exchange signaling to update alocation information of the wireless device being in an RRC inactivestate. A wireless device may transmit a RNAU indication to a basestation to update its RAN notification area, which may be employed bythe base station (e.g. anchor base station) to page the wireless devicein an RRC inactive state. Implementation of existing signaling mayresult in increased communication delay, increased packet loss rate,and/or increased call drop rate due to inefficient packet transmissionfor the wireless device of an RRC inactive state and/or an RRC idlestate.

In an RRC idle state of a wireless device, a core network entity mayrecognize that the wireless device is unreachable by a base station, andthe core network entity may not transmit packets for the wireless deviceto a base station before initiating a core network paging procedure.Unlike the RRC idle state, when a wireless device is in an RRC inactivestate, a core network entity may consider that the wireless device hasan RRC connection with a base station, and may transmit packets for thewireless device to a base station when the wireless device is notreachable by the base station. In an existing network signaling, when aRAN notification area update procedure is failed, a core network entitymay keep sending, to an anchor base station, packets for an RRC inactivestate wireless device though the anchor base station is uncertainwhether the wireless device is reachable. Example embodiments mayprevent packet transmission of a core network entity towards a basestation when a wireless device is unreachable by informing a wirelessdevice state to the core network entity.

There is a need for further enhancement in communication among networknodes (e.g. base stations, core network entity, and wireless device),for example, when there is a failure in a periodic RNAU procedure. In anexample, in some scenarios a periodic RNAU update procedure of awireless device may increase a failure rate in transmitting downlinkuser plane or control plane packets (e.g. data packets, NAS/RRCsignaling packets) for RRC inactive state wireless devices. Increasedpacket loss rate and/or increased transmission delay may degrade networksystem reliability. There is a need to improve backhaul signalingmechanism for RRC inactive state wireless devices. Example embodimentsenhance information exchange among network nodes to improve networkcommunication reliability when a wireless device is in an RRC inactivestate. Example embodiments may enhance signaling procedures when a RANnotification area update procedure is failed.

In an example embodiment, after transitioning an RRC station from an RRCconnected state to an RRC inactive state, a wireless device mayperiodically perform a RAN notification area update (RNAU) procedure bysending a RNAU indication to an anchor base station. The anchor basestation receiving the RNAU indication may consider that the wirelessdevice in the RRC inactive state stays in an RAN notification areaassociated with the anchor base station, and/or may consider that thewireless device is in a reliable service area (e.g. reachable) of a cellof the RAN notification area. During the RRC inactive state, a corenetwork entity (e.g. AMF and/or UPF) may consider that the wirelessdevice has a RRC connection with the anchor base station, and may senddownlink packets (e.g. data packets and/or control signaling packets,NAS messages) to the anchor base station. In an example embodiment, whenan anchor base station recognizes a RNAU procedure (e.g. periodic RNAUprocedure) failure of an RRC inactive state wireless device, the anchorbase station may indicate that an RNAU of the wireless device is failedand/or that the wireless device is not reachable (e.g. UE contextrelease request indicating a state transition of the wireless device toan RRC idle state).

Example embodiments may enhance system reliability by enabling a basestation to inform a core network entity of a wireless device state whena RAN notification area update procedure of the wireless device in anRRC inactive state is failed. Example embodiments may enable networknodes to reduce packet loss rate or call drop rate for an RRC inactiveand/or RRC idle state wireless device in a RAN notification area updatefailure.

In legacy LTE, a NAS identifier (typically S-TMSI) may be used toaddress the UE (wireless device) in a paging procedure. With the Rel-14Light connection WI and the introduction of RAN initiated paging, it mayhave been agreed that a RAN allocated UE identity (Resume identity) maybe used in the RRC Paging message when the paging is initiated in theRAN. One of the reasons behind this agreement may the potential securityissue if the NAS identity (S-TMSI) may be exposed on the radio interfacewithout the CN being in control of this.

In NR (new radio), a similar security issue by exposing the NAS identityon the radio interface may be likely to appear. Furthermore, using a NASidentifier at RAN initiated paging may probably also lead to additionalsignalling between the RAN and the CN since mechanisms for frequentupdates of the NAS identity may be needed. It may be also likely thatthe update mechanism may be more complex since recovery procedures maybe needed if re-allocation of the NAS identity fails.

For the reasons above, the UE may be addressed with a RAN allocated UEidentity (resume identity) at RAN initiated paging. A UE in RRC_INACTIVEmay be normally paged from the RAN, however for robustness purposes a UEin RRC_INACTIVE also may need to be reached by a CN initiated page. Toresolve from a state inconsistency situation in which the UE is inRRC_INACTIVE while the network considers the UE to be in IDLE (e.g. ifthe UE was temporarily out of coverage at the time the release messagewas sent), the UE in RRC_INACTIVE may need to respond on a CN initiatedpage containing its NAS identifier.

A UE may need to monitor and respond to a RAN initiated paging as wellas to a CN initiated paging while in RRC_INACTIVE. A RAN initiatedpaging message may include a RAN allocated UE identity whereas a CNinitiated paging message is sent with a CN allocated (NAS) identity.

At reception of the RRC Paging message while in RRC_INACTIVE the UE mayhowever behave the same regardless if the paging procedure is triggeredin the RAN or in the CN, i.e. independently of the UE identifierincluded in the message. That is, the UE may take advantage of thestored AS context and may attempt to resume the RRC connection bysending an RRC Connection Resume Request message (or equivalent) to thegNB, identifying itself with the RAN allocated UE identity sent to theUE once it may be transited to RRC_INACTIVE.

When the AS context is successfully retrieved in the network, the UE maybe transited to RRC_CONNECTED as part of the Resume procedure, see FIG.16 below.

If the AS context for some reason cannot be retrieved in the network,thus the resumption of the RRC connection fails, a fall-back proceduremay be proposed in which the gNB triggers an RRC ConnectionEstablishment procedure as a result of the failed resumption. Thesignalling flow for this scenario may be shown in FIG. 17 below.

In an example, if the resumption attempt fails it may not add anyadditional roundtrip costs between the UE and the network compared to anormal RRC Connection Establishment procedure triggered from RRC_IDLE(the UE may send a RRC Connection Request message instead of the RRCConnection Resume Request message).

The fact that the UE may keep the AS context until informed by thenetwork (in FIG. 14 at the reception of the RRC Connection Setupmessage) may also be considered as a more secure solution compared to asolution where the AS context may be simply released at reception of apaging message.

The Paging procedure in FIG. 14 and FIG. 15 may also be initiated fromthe CN if, for example, the UE may be temporarily out of coverage at thetime the release message was sent.

The following are example call flows. There may be additional messages(not shown in the call flow) that are communicated among the networknodes.

In an example embodiment as shown in FIG. 25 and FIG. 26, a first basestation may transmit, to a wireless device, at least one first messageindicating a radio resource control (RRC) state transition of thewireless device from an RRC connected state to an RRC inactive state.The at least one first message may comprise a parameter indicating avalue associated with a wireless device radio access network (RAN)notification area update timer for a periodic RAN notification areaupdate procedure. In an example, the first base station may be an anchorbase station of the wireless device. The first base station may keep aUE context of the wireless device. The UE context may comprise at leastone of PDU session configurations, security configurations, radio bearerconfigurations, logical channel configurations, resume identifierassociated with the RRC inactive state, RAN notification areainformation (e.g. a RAN area identifier, a cell identifier, a basestation identifier of a RAN notification area of the wireless device).

In an example, a wireless device in an RRC inactive state may perform anRNA update procedure when a UE RNA update timer (a periodic RANnotification area update timer value) is expired. Periodic RNA may beconfigured by a base station for a wireless device. The UE RNA updatetimer may be configured and/or (re)started when the wireless devicemakes an RRC connection, when performs an RNA update procedure, and/orvia one or more signaling message between the wireless device and thebase station. In an example the UE RNA update timer may be configuredbased on a moving speed, a network slice, a UE type, an establishedbearer type, and/or a service type of the wireless device. The basestation may transmit one or more message comprising configurationparameters, e.g. an RNA timer value, and/or an RNA counter. An RNA timerand/or counter may be restarted when the UE successfully transmits anRNA update to a base station.

In an example, a wireless device may not be able to initiate an RNAupdate procedure when a UE RNA update timer is expired for a pluralityof reasons (e.g. a plurality of system errors, moving to out of networkcoverage, and/or a power off). In an example, a first base station maydetermine that a periodic RNA update is unsuccessful if a network RNAupdate timer is expired without receiving an RNA update message from awireless device in an RRC inactive state and/or if the first basestation does not receive an RNA update message more than the number of aperiodic RNA update counter. In an example, the base station mayconsider that a periodic RNA update is unsuccessful, when a first numberof (e.g. subsequent) expected periodic RNA update messages have not beenreceived. In an example, the network RNA update timer may be longer thanthe UE RNA update timer. When one or more periodic RNA update proceduresof a wireless device fail, the base station (e.g. anchor base station)may determine a failure of a periodic RNA update of the wireless device.The determining, by the base station, the periodic RNA update failuremay be based on expiration of a network RNA update timer (e.g. RANnotification area update guard timer).

In an example, the first base station may start the network RNA updatetimer in response receiving a RNA update indication from the wirelessdevice. The RNA update indication may comprise an RRC connection resumemessage from the wireless device, a UE context retrieve request messagefrom a base station where the wireless device camps on, an Xn messageindicating an RNA update of the wireless device, and/or the like. In anexample, the first base station may start the network RNA update timerin response to communicating with the wireless device (e.g.transmitting/receiving one or more packets to/from the wireless device).In an example, the first base station may stop the network RNA updatetimer in response to communicating with the wireless device.

After determining that a periodic RNA update is unsuccessful, the firstbase station may transmit a first message to a core network entity. Thefirst message may comprise at least one of a wireless device identifierof the wireless device that failed in a periodic RNA update, an AScontext identifier of the wireless device, an RNA update failureindication for the wireless device, a wireless device context releaseindication for the wireless device in the first base station, an RRCstate transition indication informing that a RRC state of the wirelessdevice transitions to an RRC idle state, a Resume ID of the wirelessdevice and/or a core network paging request for the wireless device. Inan example, after transmitting the first message, the first base stationmay release a wireless device context (a UE context). In an example, thefirst message may comprise a UE context release request message for thewireless device. The first message may comprise a cause informationelement indicating that the wireless device is unreachable, that thewireless device is in an RRC idle state, and/or that a periodic RANnotification area update of the wireless device is failed.

In an example, the core network entity may release a UE context of thewireless device in response to receiving the first message from the basestation (e.g. anchor base station).

In an example, the core network entity, receiving the first message forthe failure of a periodic RNA update of the wireless device from thefirst base station, may configure an RRC state of the wireless device asan RRC idle state. In an example, the core network entity may keep anRRC state of the wireless device as an RRC inactive state. In anexample, the core network entity receiving the first message maytransmit a first core network paging message to a plurality of basestations. The first core network paging message may comprise at leastone of a wireless device identifier, an AS context identifier of thewireless device, a tracking area identifier (and/or a tracking areacode), a base station identifier of the first base station, an RNAidentifier associated with the wireless device, a reason of the corenetwork paging, resume ID of the wireless device and/or an actionindication for the wireless device. In an example, the action indicationmay be configured for the wireless device to perform an RRC statetransition to an RRC idle state, an RRC state transition to an RRCconnected state, an RNA update procedure, and/or a random accessprocedure. In an example, a second base station receiving a first corenetwork paging message may determine whether there is a direct interface(e.g. Xn interface) between the first base station and the second basestation at least based on the base station identifier of the first basestation.

In an example, a second base station that receives the first corenetwork paging message may broadcast/multicast a second core networkpaging message comprising the wireless device identifier, e.g., ResumeID, S-TMSI, or IMSI. In an example, the second core network pagingmessage may further comprise the AS context identifier, the RNAidentifier, the reason of the core network paging, and/or the actionindication for the wireless device. The second core network pagingmessage may be configured to initiate a random access procedure by thewireless device. In an example, the wireless device may recognize thesecond core network paging message based on at least one of the wirelessdevice identifier, the AS context identifier, and/or the RNA identifier.In an example, after receiving the second core network paging message,the wireless device may initiate a random access procedure bytransmitting a preamble message to the second base station. In anexample, the random access procedure may be a 2-stage random accessprocedure and/or a 4-stage random access procedure. In an example,during the random access procedure, the second base station may informthe wireless device of an action to take at least based on the actionindication for the wireless device, wherein the action may be at leastone of transitioning an RRC state to an RRC connected state,transitioning an RRC state to an RRC idle state, staying in an RRCinactive state, and/or initiating an RNA update procedure.

In an example, after receiving the preamble message for the randomaccess from the wireless device, the second base station may transmit acore network paging acknowledge message for the first core networkpaging message to the core network entity. The core network pagingacknowledge message may comprise a wireless device context request forthe wireless device. In an example, the core network entity may transmitan acknowledge message to the first base station for the first messagereceived form the first base station. The acknowledge message to thefirst base station may comprise a wireless device context request forthe wireless device. In an example, after receiving the preamble messagefor the random access from the wireless device, the second base stationmay transmit a wireless device context request message to the first basestation via a direct interface (e.g. an Xn interface) between the firstbase station and the second base station at least based on the basestation identifier of the first base station included in the first corenetwork paging message. In an example, the first base station maytransmit a wireless device context to the second base station indirectlyvia the core network entity and/or directly via the direct interface. Inan example, after transmitting the wireless device context to the secondbase station, the first base station may release a wireless devicecontext (a UE context).

In an example, in case that the second base station fetches the wirelessdevice context from the first base station via a direct interface, thesecond base station may transmit a path switch request for the wirelessdevice to a core network entity, and the core network entity may updatea downlink tunnel endpoint identifier for one or more bearersestablished for the wireless device between a user plane core networkentity and a RAN node, e g changing a downlink tunnel endpointidentifier from an address of the first base station to an address ofthe second base station.

In an example, after the successful core network paging procedure, thewireless device may stay in an RRC inactive state, transition to an RRCconnected state, and/or transition to an RRC idle state. In case thatthe wireless device stays in an RRC inactive state or transitions to anRRC connected state, the second base station may keep a wireless devicecontext of the wireless device and may maintain one or more bearers forthe wireless device between the second base station and a user planecore network entity. If the wireless device stays in an RRC inactivestate, the second base station may become an anchor base station for thewireless device. If the wireless device transitions to an RRC connectedstate, the second base station may initiate an RRC state transition ofthe wireless device to an RRC inactive state, and the second basestation may become an anchor base station. In case that the wirelessdevice transitions to an RRC idle state, the second base station may notrequest a wireless device context to the first base station and/or tothe core network entity.

In an example, if a wireless device in an RRC inactive state does notperform an RNA update procedure before a UE RNA update timer (a periodicRAN notification area update timer value) is expired, the wirelessdevice may determine that a periodic RNA update is failed. The may UEmay start an RNA update timer in response to an RRC message configuringperiodic RNA timer in the UE and the UE transitioning to inactive RRCstate. The UE may restart the UE RNA timer when the UE transmits an RNAupdate.

In an example, if the periodic RNA update failure occurs, the wirelessdevice may transition its RRC state to an RRC idle state immediately,after an expiration of another timer, and/or after failing in performingan RNA update procedure more than a number of a periodic RNA updatecounter. For example, when a UE RNA update procedure is unsuccessful afirst number of (e.g. consecutive) times, the UE may determine that theperiodic RNA update failed. In an example, a base station may transmitto the wireless device a configuration message comprising periodic RNAupdate timer and/or counter values.

In an example, a first base station may determine, for a wirelessdevice, a periodic RNA failure based on one or more criteria comprisingexpiry of a periodic RAN notification area update timer. The first basestation may transmit, to a core network entity, a first message inresponse to determining the periodic RNA failure, wherein the firstmessage may comprise a first wireless device identifier of the wirelessdevice, and/or the first message may indicate the periodic RNA failurefor the wireless device. The first message further may comprise a firstindication indicating that the first base station releases a wirelessdevice context. The first base station may further release a wirelessdevice context of the wireless device. The first message may furthercomprise a second indication indicating that a first time durationassociated with RNA update period is elapsed and no RNA update isreceived. The second base station may further receive, from the corenetwork entity, a second message comprising a first paging and a secondwireless device identifier of the wireless device. The second basestation may broadcast and/or multicast a third message comprising asecond paging and the second wireless device identifier. The second basestation may receive, from the wireless device, a fourth messagecomprising an acknowledgement of the second paging, wherein the wirelessdevice may recognize the second paging request at least based on thesecond wireless device identifier. The second base station may transmit,to the core network entity, a fifth message indicating a response to thesecond message.

In an example, the first base station may further receive a fifthmessage comprising a request of a wireless device context for thewireless device. The first base station may transmit a sixth messagecomprising the wireless device context. The first base station mayrelease the wireless device context. The wireless device may furthertransition a radio resource control state to a radio resource controlidle state in response to a paging message from a base station. Thewireless device may further transition a radio resource control state toa radio resource control idle state after receiving the paging message.The wireless device may be in a radio resource control RRC inactivestate after receiving the paging message. The second base station mayfurther transmit to the wireless device at least one of the following: amessage comprising a radio resource control state transition indicationcompleting a radio resource control state transition from a radioresource control connected state to a radio resource control inactivestate, a message comprising a radio access network notification areaupdate accept, and/or one of one or more packets. The second basestation may receive, from the wireless device, at least one of thefollowing: a message comprising a radio access network notification areaupdate request, one of one or more packets received by the first basestation from the wireless device, and/or a message comprising anacknowledgement of a radio access network notification area paging.

In an example, the first base station may further release a RAN contextof the wireless device. The first base station and/or the core networkentity may transition a radio resource control state from an RRCinactive state to an RRC idle state. In an example, the wireless devicemay transition to an RRC idle state from an RRC inactive state if asecond criteria is met. The first base station may transmit to thewireless device one or more messages comprising one or moreconfiguration parameters of an RNA, the one or more configurationparameter comprising a parameter indicating a value for a periodic RANnotification area update timer value. In an example, the first basestation may transmit to the wireless device one or more criteriacomprising reaching a periodic RAN notification area update counter. Ifa number of failing in an RNA update reaches the periodic RANnotification area update counter, the wireless device may transition toan RRC idle state.

In an example, a wireless device may receive, from a base station, oneor more first messages comprising one or more configuration parametersof an RNA, the one or more configuration parameter comprising aparameter indicating a value for a periodic RAN notification area updatetimer value. The wireless device may determine a periodic RNA updatefailure based on one or more criteria comprising expiry of the periodicRAN notification area update timer. The wireless device may transitionto an RRC idle state in response to determining the periodic RNA updatefailure.

Embodiments may be configured to operate as needed. The disclosedmechanism may be performed when certain criteria are met, for example,in a wireless device, a base station, a radio environment, a network, acombination of the above, and/or the like. Example criteria may bebased, at least in part, on for example, wireless device or network nodeconfigurations, traffic load, initial system set up, packet sizes,traffic characteristics, a combination of the above, and/or the like.When the one or more criteria are met, various example embodiments maybe applied. Therefore, it may be possible to implement exampleembodiments that selectively implement disclosed protocols.

According to various embodiments, a device such as, for example, awireless device, off-network wireless device, a base station, and/or thelike, may comprise one or more processors and memory. The memory maystore instructions that, when executed by the one or more processors,cause the device to perform a series of actions. Embodiments of exampleactions are illustrated in the accompanying figures and specification.Features from various embodiments may be combined to create yet furtherembodiments.

FIG. 27 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 2710, a first base station may receive from afirst core network entity, one or more packets for a wireless device ina radio resource control (RRC) inactive state. At 2720, the first basestation may initiate a radio access network (RAN) paging procedurecomprising sending at least one RAN paging message to at least onesecond base station. The at least one RAN paging message may comprise afirst identifier of the wireless device. At 2730, the first base stationmay determine a failure of the RAN paging procedure in response to notreceiving a response of the at least one RAN paging message. At 2740,the first base station may send a first message to a second core networkentity in response to the failure of the RAN paging procedure. At 2750,the first base station may receive a second message from the second corenetwork entity in response to the first message. The second message maycomprise a tunnel endpoint identifier of a third base station forforwarding the one or more packets. At 2760, the first base station maysend to the third base station, the one or more packets based on thetunnel endpoint identifier.

According to an embodiment, the second core network entity may initiate,in response to receiving the first message, a core network pagingprocedure. The core network paging procedure may comprise sending afirst paging message to the third base station. The first paging messagemay comprise a second identifier of the wireless device. The second corenetwork entity may receive from the third base station, a third messagein response to the first paging message. The third message may comprisethe tunnel endpoint identifier of the third base station. According toan embodiment, the first core network entity may comprise a controlplane core network node. The second core network entity may comprise auser plane core network node. According to an embodiment, the sending ofthe one or more packets may be via a direct tunnel between the firstbase station and the third base station. The direct tunnel may beassociated with the tunnel endpoint identifier. According to anembodiment, the tunnel endpoint identifier may comprise an internetprotocol (IP) address of the third base station. According to anembodiment, the first message may indicate the failure of the RAN pagingprocedure. According to an embodiment, the at least one RAN pagingmessage may comprise at least one of: a RAN notification information; acontext identifier of the wireless device; a reason of initiating theRAN paging procedure; and/or the like. According to an embodiment, theat least one second base station may transmit a second RAN pagingmessage via a radio interface in response to receiving the at least oneRAN paging message.

FIG. 28 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 2810, a third base station may receive from asecond core network entity, a first paging message for a wirelessdevice. The first paging message may comprise a second identifier of thewireless device. At 2820, the third base station may transmit, inresponse to receiving the first paging message, a second paging messagefor the wireless device via a radio interface. At 2830, the third basestation may receive from the wireless device, in response to the firstpaging message, a random access preamble for a radio resource control(RRC) connection. At 2840, the third base station may transmit to thesecond core network entity, in response to the RRC connection, a thirdmessage comprising a tunnel endpoint identifier of the third basestation. At 2850, the third base station may receive from a first basestation, one or more packets based on the tunnel endpoint identifier.

According to an embodiment, the second core network entity may comprisea user plane core network node. According to an embodiment, thereceiving of the one or more packets may be via a direct tunnel betweenthe first base station and the third base station. The direct tunnel maybe associated with the tunnel endpoint identifier. According to anembodiment, the tunnel endpoint identifier may comprise an internetprotocol (IP) address of the third base station.

FIG. 29 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 2910, a first base station may receive from afirst core network entity, one or more packets for a wireless device. At2920, the first base station may initiate a paging procedure. The pagingprocedure may comprise sending at least one paging message to at leastone second base station. The at least one paging message may comprise afirst identifier of the wireless device. At 2930, the first base stationmay send a first message to a second core network entity in response todetermining a failure of the paging procedure. At 2940, the first basestation may receive a second message from the second core network entityin response to the first message. The second message may comprise atunnel identifier of a third base station for forwarding the one or morepackets. At 2950, the first base station may send to the third basestation, the one or more packets based on the tunnel identifier.

According to an embodiment, the paging procedure may comprise a radioaccess network (RAN) paging procedure. According to an embodiment, thetunnel identifier may comprise a tunnel endpoint identifier. Accordingto an embodiment, the wireless device may be in a radio resource controlinactive state. According to an embodiment, the determining the failuremay be in response to not receiving a response of the at least onepaging message. According to an embodiment, the first message mayindicate the failure of the paging procedure.

FIG. 30 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 3010, a first base station may transmit to asecond base station, a first message comprising a first radio accessnetwork (RAN) area identifier of the first base station. At 3020, thefirst base station may receive from the second base station, a secondmessage comprising a second RAN area identifier of the second basestation. At 3030, the first base station may transmit to a wirelessdevice, at least one radio resource control (RRC) message. The at leastone RRC message may comprise the first RAN area identifier. The at leastone RRC message may indicate a state transition of the wireless deviceto an RRC inactive state. At 3040, the first base station may receiveone or more packets for the wireless device. At 3050, the first basestation may transmit to the second base station, and in response toreceiving the one or more packets, a RAN paging message when the firstRAN area identifier is identical to the second RAN area identifier. TheRAN paging message may comprise an identifier of the wireless device andthe first RAN area identifier.

According to an embodiment, the first message may further comprise afirst cell identifier of a first cell of the first base station. Thefirst cell may be associated with the first RAN area identifier.According to an embodiment, the second message may further comprise asecond cell identifier of a second cell of the second base station. Thesecond cell may be associated with the second RAN area identifier.According to an embodiment, the transmitting of the RAN paging messagemay be in response to the wireless device being in the RRC inactivestate. According to an embodiment, the first base station may furtherreceive from the second base station, a third message in response to theRAN paging message. According to an embodiment, the first base stationmay further transmit to the second base station, the one or more packetsfor the wireless device in response to the third message. According toan embodiment, the first base station may keep a wireless device contextof the wireless device at least during a time in which the wirelessdevice is in the RRC inactive state. The wireless device context maycomprise at least one of: a bearer configuration information; a logicalchannel configuration information; a security information; and/or thelike. According to an embodiment, the first message may comprise atleast one of: an interface setup request message; an interface setupresponse message; a base station configuration update message; and/orthe like. According to an embodiment, the first base station may receivethe one or more packets from a core network entity. According to anembodiment, the first base station may further transmit one or more RANpaging messages to one or more third base stations associated with thefirst RAN identifier.

FIG. 31 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 3110, a second base station may receive froma first base station, a first message comprising a first radio accessnetwork (RAN) area identifier of the first base station. At 3120, thesecond base station may transmit to the first base station, a secondmessage comprising a second RAN area identifier of the second basestation. At 3130, the second base station may receive from the firstbase station, a RAN paging message for a wireless device when the firstRAN area identifier is identical to the second RAN area identifier. Thewireless device may be: in a radio resource control (RRC) inactivestate; and assigned with the first RAN area identifier. According to anembodiment, the RAN paging message may comprise an identifier of thewireless device and the first RAN area identifier.

FIG. 32 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 3210, a first base station may receive from asecond base station, a second message comprising a second radio accessnetwork (RAN) area identifier of the second base station. At 3220, thefirst base station may transmit to a wireless device, at least one thirdmessage comprising a first RAN area identifier. The at least one thirdmessage may indicate a state transition of the wireless device to aradio resource control inactive state. At 3230, the first base stationmay receive one or more packets for the wireless device. At 3240, thefirst base station may transmit to the second base station and inresponse to receiving the one or more packets, a RAN paging message whenthe first RAN area identifier is identical to the second RAN areaidentifier. The RAN paging message may comprise an identifier of thewireless device and the first RAN area identifier. According to anembodiment, the first base station may further transmit to the secondbase station, a first message comprising a first RAN area identifier ofthe first base station.

FIG. 33 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 3310, a first base station may receive from asecond base station, at least one first packet associated with awireless device. At 3320, the first base station may receive from a corenetwork entity, at least one second packet for the wireless device whenthe wireless device is in a radio resource control (RRC) inactive state.At 3330, the first base station may transmit a first RAN paging messageto a third base station of a radio access network (RAN) area associatedwith the wireless device and in response to a first time duration beinglarger than a first time value. The first time duration may comprise atime duration between the receiving of the at least one first packet andthe receiving of the at least one second packet. At 3340, the first basestation may transmit a second RAN paging message to the second basestation regardless of the first time duration being smaller or largerthan the first time value. At 3350, the first base station may transmitat least one second packet to one of the second base station or thethird base station based on a response received for one of the first RANpaging message or the second RAN paging message.

According to an embodiment, the RAN area may be associated with a RANnotification area. According to an embodiment, the first RAN pagingmessage or the second RAN paging message may comprise: an identifier ofthe wireless device; and a RAN area information of the RAN area.According to an embodiment, the at least one first packet may beassociated with at least one of: an uplink data transmission of thewireless device being in the RRC inactive state; a data transmission; aRAN notification area update procedure; or a state transition of thewireless device from a RRC inactive state connected state to the RRCinactive state. According to an embodiment, the first time value may bebased on moving speed of the wireless device. According to anembodiment, the first base station may keep a wireless device context ofthe wireless device at least during a time in which the wireless deviceis in the RRC inactive state. The wireless device context may compriseat least one of: a bearer configuration information; a logical channelconfiguration information; a packet data convergence protocolconfiguration information; or a security information. According to anembodiment, the first base station may be associated with the RAN area.According to an embodiment, the first base station may further transmitto the wireless device, at least one RRC message comprising RAN areainformation of the RAN area. The at least one RRC message may indicate astate transition of the wireless device to the RRC inactive state.

According to an embodiment, the second base station may transmit a firstpaging message via a first cell of the RAN area associated with thewireless device in response to: receiving the second RAN paging message;and a second time duration being larger than a second time value. Thesecond time duration may comprise a time duration between receiving theat least one first packet from the wireless device and the receiving ofthe second RAN paging message. The second base station may transmit asecond paging message via a second cell regardless of the second timeduration being smaller or larger than the second time value wherein thesecond base station may have received the at least one first packet fromthe wireless device via the second cell. According to an embodiment, thesecond base may further transmit the at least one second packet via oneof the first cell or the second cell based on a response received forone of the first paging message or the second paging message.

FIG. 34 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 3410, a first base station may receive from asecond base station, at least one first packet associated with awireless device. At 3420, the first base station may receive from a corenetwork entity, at least one second packet for the wireless device whenthe wireless device is in a radio resource control (RRC) inactive state.At 3430, the first base station may determine whether a time durationbetween the receiving of the at least one first packet and the receivingof the at least one second packet is larger than a first time value.When the time duration is larger than the first time value (3440), thefirst base station may transmit a first RAN paging message to a thirdbase station of a radio access network (RAN) area associated with thewireless device at 3445. When the time duration is smaller than or equalto the first time value (3450), the first base station may transmit asecond RAN paging message to the second base station at 3455. At 3460,the first base station may transmit at least one second packet to one ofthe second base station or the third base station based on a responsereceived for one of the first RAN paging message or the second RANpaging message.

FIG. 35 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 3510, a first base station may receive from awireless device, at least one first packet via a first cell of the firstbase station. At 3520, the first base station may receive from a corenetwork entity, at least one second packet for the wireless device whenthe wireless device is in a radio resource control inactive state. At3530, the first base station may transmit a first RAN paging message toa second base station of a radio access network (RAN) area associatedwith the wireless device and in response to a first time duration beinglarger than a first time value. The first time duration may comprise atime duration between the receiving of the at least one first packet andthe receiving of the at least one second packet. At 3540, the first basestation may transmit a second RAN paging message via one or more secondcells of the RAN area regardless of the first time duration beingsmaller or larger than the first time value. The one or more secondcells may comprise the first cell. At 3550, the first base station maytransmit the at least one second packet to the wireless device via oneof the one or more second cells or the second base station based on aresponse received for one of the first RAN paging message or the secondRAN paging message.

FIG. 36 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 3610, a wireless device may receive from abase station, at least one first message comprising configurationparameters of at least one of: at least one logical channel; or at leastone radio bearer. At 3620, the wireless device may receive from the basestation, a second message indicating a radio resource control (RRC)state transition of the wireless device from an RRC connected state toan RRC inactive state. At 3630, the wireless device being in the RRCinactive state may select a first cell based on the configurationparameters. At 3640, the wireless device may transmit to the basestation, a random access preamble via the first cell.

According to an embodiment, the configuration parameters may furthercomprises at least one of: a first cell identifier of the first cell; atleast one logical channel identifier of the at least one logicalchannel; or at least one radio bearer identifier of the at least oneradio bearer. According to an embodiment, the configuration parametersmay indicate association of the at least one logical channel or the atleast one radio bearer with the first cell. According to an embodiment,the configuration parameters may indicate association of the at leastone logical channel or the at least one radio bearer with at least oneof: one or more cell types; or one or more frequency bands. According toan embodiment, the configuration parameters may further indicateassociation of a first network slice with at least one of: the firstcell; one or more cell types; or one or more frequency bands. Accordingto an embodiment, the at least one logical channel or the at least oneradio bearer may be associated with a first network slice. According toan embodiment, the base station may keep a wireless device context ofthe wireless device at least during a time in which the wireless deviceis in the RRC inactive state. The wireless device context may comprisingat least one of: a bearer configuration information; a logical channelconfiguration information; a packet data convergence protocolconfiguration information; a security information; and/or the like.According to an embodiment, the selecting of the first cell may be inresponse to an uplink buffer comprising one or more packets associatedwith at least one of: the at least one logical channel; or the at leastone radio bearer. According to an embodiment, the transmitting of therandom access preamble message may be in response to at least one of: anuplink buffer comprising one or more packets; a paging indication fromthe base station; moving to a first radio access network notificationarea; or moving to a first tracking area.

FIG. 37 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 3710, a base station may transmit to awireless device, at least one first message. The at least one firstmessage may comprise configuration parameters of at least one of: atleast one logical channel; or at least one radio bearer. At 3720, thebase station may transmit to the wireless device, a second messageindicating a radio resource control (RRC) state transition of thewireless device from an RRC connected state to an RRC inactive state. At3730, the base station may receive from the wireless device, a randomaccess preamble via the first cell selected by the wireless device basedon the configuration parameters. The wireless device may be in the RRCinactive state. According to an embodiment, the configuration parametersmay further comprises at least one of: a first cell identifier of thefirst cell; at least one logical channel identifier of the at least onelogical channel; or at least one radio bearer identifier of the at leastone radio bearer.

FIG. 38 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 3810, a first base station may transmit to awireless device, at least one first message indicating a radio resourcecontrol (RRC) state transition of the wireless device from an RRCconnected state to an RRC inactive state. The at least one first messagemay comprise a parameter indicating a value associated with a wirelessdevice radio access network (RAN) notification area update timer for aperiodic RAN notification area update procedure. At 3820, the first basestation may receive a second message indicating a RAN notification areaupdate by the wireless device in response to expiry of the wirelessdevice RAN notification area update timer. At 3830, the first basestation may start a network RAN notification area update timer inresponse to the receiving of the second message. At 3840, the first basestation may transmit to a core network entity and in response to anexpiration of the network RAN notification area update timer, a thirdmessage indicating a wireless device context release request for thewireless device. The third message may comprise an identifier of thewireless device.

According to an embodiment, the at least one first message may furthercomprise a RAN notification area information associated with thewireless device. The RAN notification area information may comprise atleast one of: a RAN area identifier; or a cell identifier. According toan embodiment, the first base station may further release a wirelessdevice context of the wireless device based on the expiration of thenetwork RAN notification area update timer. According to an embodiment,the third message may further indicate that the wireless device fails ina period RAN notification area update. According to an embodiment, thecore network entity may determine the wireless device as being in anidle state in response to receiving the third message. According to anembodiment, the first base station may keep a wireless device context ofthe wireless device at least during a time in which the wireless deviceis in the RRC inactive state. The wireless device context may compriseat least one of: a bearer configuration information; a logical channelconfiguration information; a packet data convergence protocolconfiguration information; a security information, and/or the like.According to an embodiment, the wireless device RAN notification areaupdate timer may be configured based on at least one of: a moving speedof the wireless device; a wireless device type of the wireless device; anetwork slice of the wireless device; a bearer of the wireless device;and/or the like. According to an embodiment, the core network entity mayfurther transmit to a second base station, a paging message for thewireless device based on the third message. The core network entity mayfurther receive from the second base station, a response message to thepaging message. According to an embodiment, the wireless device maytransition a RRC state from the RRC inactive state to a RRC idle statein response to failing in a period RAN notification area update.According to an embodiment, the second message may comprise an RRCconnection resume request message.

FIG. 39 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 3910, a first base station may transmit to awireless device, at least one first message indicating a radio resourcecontrol (RRC) state transition of the wireless device from an RRCconnected state to an RRC inactive state. At 3920, the first basestation may receive from the wireless device, a second messageindicating a RAN notification area update by the wireless device. At3930, the first base station may start a network radio access network(RAN) notification area update timer in response to the receiving of thesecond message. At 3940, the first base station may transmit to a corenetwork entity and in response to an expiration of the network RANnotification area update timer, a third message indicating a wirelessdevice context release request for the wireless device. The thirdmessage may comprise an identifier of the wireless device.

FIG. 40 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 4010, a first base station may transmit to awireless device, at least one first message indicating a radio resourcecontrol (RRC) state transition of the wireless device from an RRCconnected state to an RRC inactive state. The at least one first messagemay comprise a parameter indicating a value associated with a wirelessdevice radio access network (RAN) notification area update timer for aperiodic RAN notification area update procedure. At 4020, the first basestation may receive a second message indicating a RAN notification areaupdate by the wireless device in response to expiry of the wirelessdevice RAN notification area update timer. At 4030, the first basestation may transmit to a core network entity and in response to notreceiving a RAN notification area update within a time duration, a thirdmessage indicating a wireless device context release request for thewireless device. The time period may be longer than the value associatedwith the wireless device RAN notification area update timer. Accordingto an embodiment, the third message may comprise an identifier of thewireless device.

FIG. 41 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 4110, a first base station may transmit to awireless device, at least one first message indicating a radio resourcecontrol (RRC) state transition of the wireless device from an RRCconnected state to an RRC inactive state. The at least one first messagemay comprise a parameter indicating a first value associated with awireless device radio access network (RAN) notification area updatetimer for a periodic RAN notification area update procedure. At 4120,the wireless device may start a RAN notification area update timer inresponse to the RRC state transition. At 4130, the first base stationmay receive a second message indicating a RAN notification area updatewith a second value by the wireless device in response to expiry of thewireless device RAN notification area update timer. At 4140, the firstbase station may start a network RAN notification area update timer inresponse to the receiving of the second message. At 4140, the first basestation may transmit to a core network entity and in response to anexpiration of the network RAN notification area update timer, a thirdmessage indicating a wireless device context release request for thewireless device. The third message may comprise an identifier of thewireless device. The second value of the network RAN notification areaupdate timer may be larger than the first value of the wireless deviceRAN notification area update timer.

A base station may communicate with a mix of wireless devices. Wirelessdevices and/or base stations may support multiple technologies, and/ormultiple releases of the same technology. Wireless devices may have somespecific capability(ies) depending on wireless device category and/orcapability(ies). A base station may comprise multiple sectors. When thisdisclosure refers to a base station communicating with a plurality ofwireless devices, this disclosure may refer to a subset of the totalwireless devices in a coverage area. This disclosure may refer to, forexample, a plurality of wireless devices of a given LTE or 5G releasewith a given capability and in a given sector of the base station. Theplurality of wireless devices in this disclosure may refer to a selectedplurality of wireless devices, and/or a subset of total wireless devicesin a coverage area which perform according to disclosed methods, and/orthe like. There may be a plurality of base stations or a plurality ofwireless devices in a coverage area that may not comply with thedisclosed methods, for example, because those wireless devices or basestations perform based on older releases of LTE or 5G technology.

In this disclosure, “a” and “an” and similar phrases are to beinterpreted as “at least one” and “one or more.” Similarly, any termthat ends with the suffix “(s)” is to be interpreted as “at least one”and “one or more.” In this disclosure, the term “may” is to beinterpreted as “may, for example.” In other words, the term “may” isindicative that the phrase following the term “may” is an example of oneof a multitude of suitable possibilities that may, or may not, beemployed to one or more of the various embodiments.

If A and B are sets and every element of A is also an element of B, A iscalled a subset of B. In this specification, only non-empty sets andsubsets are considered. For example, possible subsets of B={cell1,cell2} are: {cell1}, {cell2}, and {cell1, cell2}. The phrase “based on”(or equally “based at least on”) is indicative that the phrase followingthe term “based on” is an example of one of a multitude of suitablepossibilities that may, or may not, be employed to one or more of thevarious embodiments. The phrase “in response to” (or equally “inresponse at least to”) is indicative that the phrase following thephrase “in response to” is an example of one of a multitude of suitablepossibilities that may, or may not, be employed to one or more of thevarious embodiments. The phrase “depending on” (or equally “depending atleast to”) is indicative that the phrase following the phrase “dependingon” is an example of one of a multitude of suitable possibilities thatmay, or may not, be employed to one or more of the various embodiments.The phrase “employing/using” (or equally “employing/using at least”) isindicative that the phrase following the phrase “employing/using” is anexample of one of a multitude of suitable possibilities that may, or maynot, be employed to one or more of the various embodiments.

The term configured may relate to the capacity of a device whether thedevice is in an operational or non-operational state. Configured mayalso refer to specific settings in a device that effect the operationalcharacteristics of the device whether the device is in an operational ornon-operational state. In other words, the hardware, software, firmware,registers, memory values, and/or the like may be “configured” within adevice, whether the device is in an operational or nonoperational state,to provide the device with specific characteristics. Terms such as “acontrol message to cause in a device” may mean that a control messagehas parameters that may be used to configure specific characteristics ormay be used to implement certain actions in the device, whether thedevice is in an operational or non-operational state

In this disclosure, various embodiments are disclosed. Limitations,features, and/or elements from the disclosed example embodiments may becombined to create further embodiments within the scope of thedisclosure.

In this disclosure, parameters (or equally called, fields, orInformation elements: IEs) may comprise one or more information objects,and an information object may comprise one or more other objects. Forexample, if parameter (IE) N comprises parameter (IE) M, and parameter(IE) M comprises parameter (IE) K, and parameter (IE) K comprisesparameter (information element) J. Then, for example, N comprises K, andN comprises J. In an example embodiment, when one or more messagescomprise a plurality of parameters, it implies that a parameter in theplurality of parameters is in at least one of the one or more messages,but does not have to be in each of the one or more messages.

Furthermore, many features presented above are described as beingoptional through the use of “may” or the use of parentheses. For thesake of brevity and legibility, the present disclosure does notexplicitly recite each and every permutation that may be obtained bychoosing from the set of optional features. However, the presentdisclosure is to be interpreted as explicitly disclosing all suchpermutations. For example, a system described as having three optionalfeatures may be embodied in seven different ways, namely with just oneof the three possible features, with any two of the three possiblefeatures or with all three of the three possible features.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an element thatperforms a defined function and has a defined interface to otherelements. The modules described in this disclosure may be implemented inhardware, software in combination with hardware, firmware, wetware (i.e.hardware with a biological element) or a combination thereof, all ofwhich may be behaviorally equivalent. For example, modules may beimplemented as a software routine written in a computer languageconfigured to be executed by a hardware machine (such as C, C++,FORTRAN, Java, Basic, Matlab or the like) or a modeling/simulationprogram such as Simulink, Stateflow, GNU Octave, or LabVIEWMathScript.Additionally, it may be possible to implement modules using physicalhardware that incorporates discrete or programmable analog, digitaland/or quantum hardware. Examples of programmable hardware comprise:computers, microcontrollers, microprocessors, application-specificintegrated circuits (ASICs); field programmable gate arrays (FPGAs); andcomplex programmable logic devices (CPLDs). Computers, microcontrollersand microprocessors are programmed using languages such as assembly, C,C++ or the like. FPGAs, ASICs and CPLDs are often programmed usinghardware description languages (HDL) such as VHSIC hardware descriptionlanguage (VHDL) or Verilog that configure connections between internalhardware modules with lesser functionality on a programmable device. Theabove mentioned technologies are often used in combination to achievethe result of a functional module.

The disclosure of this patent document incorporates material which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, for the limited purposes required by law, butotherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevantart(s) that various changes in form and detail can be made thereinwithout departing from the scope. In fact, after reading the abovedescription, it will be apparent to one skilled in the relevant art(s)how to implement alternative embodiments. Thus, the present embodimentsshould not be limited by any of the above described exemplaryembodiments.

In addition, it should be understood that any figures which highlightthe functionality and advantages, are presented for example purposesonly. The disclosed architecture is sufficiently flexible andconfigurable, such that it may be utilized in ways other than thatshown. For example, the actions listed in any flowchart may bere-ordered or only optionally used in some embodiments.

Further, the purpose of the Abstract of the Disclosure is to enable theU.S. Patent and Trademark Office and the public generally, andespecially the scientists, engineers and practitioners in the art whoare not familiar with patent or legal terms or phraseology, to determinequickly from a cursory inspection the nature and essence of thetechnical disclosure of the application. The Abstract of the Disclosureis not intended to be limiting as to the scope in any way.

Finally, it is the applicant's intent that only claims that include theexpress language “means for” or “step for” be interpreted under 35U.S.C. 112. Claims that do not expressly include the phrase “means for”or “step for” are not to be interpreted under 35 U.S.C. 112.

What is claimed is:
 1. A method by a first base station comprising: receiving, from a second base station, cell related information including one or more second cell identifiers of one or more cells supported by the second base station; identifying a packet for a wireless device in a radio resource control (RRC) inactive state supporting a radio access network (RAN) paging; and transmitting, to the second base station, in response to identifying the packet, a RAN paging message based on a first RAN area identifier of one or more cells supported by the first base station and a second RAN area identifier of the one or more cells supported by the second base station.
 2. The method of claim 1, wherein the RAN paging message comprises an identifier of the wireless device for the RAN paging, paging discontinuous reception (DRX) information and RAN paging area information of a RAN paging area for the RAN paging.
 3. The method of claim 2, wherein the RAN paging area information comprises the first RAN area identifier, the second RAN area identifier, the one or more second cell identifiers, and one or more first cell identifiers of the one or more cells supported by the first base station.
 4. The method of claim 1, wherein the second RAN area identifier is included in the cell related information.
 5. The method of claim 1, further comprising transmitting, to the second base station, at least one of: one or more first cell identifiers of the one or more cells supported by the first base station; or the first RAN area identifier.
 6. The method of claim 1, further comprising: transmitting, to the wireless device, at least one RRC release message comprising the first RAN area identifier, the second RAN area identifier, the one or more second cell identifiers, and one or more first cell identifiers of the one or more cells supported by the first base station, wherein the at least one RRC release message indicates a state transition of the wireless device to the RRC inactive state.
 7. The method of claim 1, wherein the transmitting the RAN paging message is further based on the wireless device being in the RRC inactive state.
 8. A method by a second base station comprising: transmitting, to a first base station, cell related information including one or more second cell identifiers of one or more cells supported by the second base station; and receiving, from the first base station, a radio access network (RAN) paging message for a wireless device based on a first RAN area identifier of one or more cells supported by the first base station and a second RAN area identifier of the one or more cells supported by the second base station, wherein the wireless device is in a radio resource control (RRC) inactive state supporting a RAN paging.
 9. The method of claim 8, wherein the RAN paging message indicates a state transition of the wireless device from the RRC inactivate state to at least one of: an RRC idle state; or an RRC connected state.
 10. The method of claim 8, further comprising transmitting, to the wireless device, one or more paging messages based on the RAN paging message.
 11. The method of claim 8, wherein the RAN paging message comprises an identifier of the wireless device for the RAN paging, paging discontinuous reception (DRX) information and RAN paging area information of a RAN paging area for the RAN paging.
 12. The method of claim 11, wherein the RAN paging area information comprises the first RAN area identifier, the second RAN area identifier, the one or more second cell identifiers, and one or more first cell identifiers of the one or more cells supported by the first base station.
 13. The method of claim 8, wherein the second RAN area identifier is included in the cell related information.
 14. The method of claim 8, further comprising: receiving, by the second base station from the first base station, at least one of: one or more first cell identifiers of the one or more cells supported by the first base station; or the first RAN area identifier.
 15. The method of claim 8, wherein the wireless device is in the RRC inactive state based on the wireless device receiving at least one RRC release message that indicates a state transition of the wireless device to the RRC inactive state, and wherein the at least one RRC release message comprises the first RAN area identifier, the second RAN area identifier, the one or more second cell identifiers, and one or more first cell identifiers of the one or more cells supported by the first base station.
 16. The method of claim 8, wherein the receiving the RAN paging message is further based on the wireless device being in the RRC inactive state.
 17. An apparatus by a first base station in a communication, the apparatus comprising: a transceiver configured to transmit and receive data; and at least one processor configured to: control to the transceiver to receive, from a second base station, cell related information including one or more second cell identifiers of one or more cells supported by the second base station, identify a packet for a wireless device in a radio resource control (RRC) inactive state supporting a radio access network (RAN) paging, and control to the transceiver to transmit, to the second base station, in response to identifying the packet, a RAN paging message based on a first RAN area identifier of one or more cells supported by the first base station and a second RAN area identifier of the one or more cells supported by the second base station.
 18. The apparatus of claim 17, wherein the RAN paging message comprises an identifier of the wireless device for the RAN paging, paging discontinuous reception (DRX) information and RAN paging area information of a RAN paging area for the RAN paging, wherein the RAN paging area information comprises the first RAN area identifier, the second RAN area identifier, the one or more second cell identifiers, and one or more first cell identifiers of the one or more cells supported by the first base station, and wherein the second RAN area identifier is included in the cell related information.
 19. The apparatus of claim 17, wherein the at least one processor is further configured to: control to the transceiver to transmit, to the second base station, at least one of: one or more first cell identifiers of the one or more cells supported by the first base station, or the first RAN area identifier.
 20. The apparatus of claim 17, wherein the at least one processor is further configured to: control to the transceiver to transmit, to the wireless device, at least one RRC release message comprising the first RAN area identifier, the second RAN area identifier, the one or more second cell identifiers, and one or more first cell identifiers of the one or more cells supported by the first base station, wherein the at least one RRC release message indicates a state transition of the wireless device to the RRC inactive state, and wherein the transmitting the RAN paging message is further based on the wireless device being in the RRC inactive state. 